When the revs go high, try disconnecting the IAC valve to see if it corrects the issue or stalls out the engine. There is definitely too much air somehow getting to the engine, which is causing the issue.

 

Yes. You MUST have leaking extra air to raise rpm like that as the car does not have electronic throttle. Need to know engine type, there are 3 in that year.

Vacuum leak or IAC messed up. Get a new mechanic.

 

Hopefully this goes through. I have the 2.0L Zetec. Sorry for the late response, it's been impossible for me to verify my account for some reason, I had to reach out to support. Edit: I replaced the IAC Valve over the weekend (my god what a pain)and the issue still persists. The PCV valve hose was replaced a few years ago and it's the one with the shielding to protect it. I wonder if I have an electrical gremlin somewhere because I can hear the relay inside the car clicking. Or could a vacuum leak be causing that as well?

 

If you used anything but a motorcfaft pcv hose I would suspect it first. The elbow to the pcv valve is another failure point as well as the pcv grommet.

 

Okay, I was able to get it to run until it's stalled. I noticed that when the car stalled out if I am staring at the front of the engine the front left where the passenger side is made a hissing noise after it cut out so I'm guessing that's where my vacuum leak would be correct? It's towards the back left.

 

PCV hose in back of motor by that location. Also, a new throttle body if vacuum leak at it due to incompetent tightening, it being plastic and warps easy if too tight. A new base gasket MUSTY be used too and common to try to reuse them as they 'look OK'. Big mistake. Vacuum leak.

 

I'll definitely be checking it out after work, I might have a spare new hose, I'll have to check (I bought a hose because the elbow and hose came as one piece and the elbow broke once).

 

Update: I replaced the evap purge valve thinking that was the issue because I thought that's where the hiss was coming from. No luck. one thing I did notice, I don't know if the surge is so strong or I'm losing vacuum on the brakes because they're all the way to the floor when it happens and the brakes just seem weak.

 

Possible the brake booster hose has pulled out of the intake partially.

 

The booster may even be bad.

 

The car gets screwier and screwier. I scanned the OBD and it told me that the engine knock sensor was bad. Some of the process of removing it and the hazards start flashing and then it just starts acting all possessed. I'm including a video.

 

Have you replaced the battery? That looks like what happens when the alarm is triggered by a low battery.

 

Battery has been replaced and it has been plagued by an electrical gremlin that would drain the battery. I replaced the cable that goes from the alternator to the battery because a bad cable with a bad ground somewhere could cause the issue.

 

Never work on electrical components with the battery connected. Always remove the negative battery terminal. Positive as well if messing with the starter or alternator.

 

While I would agree, I wasn't even touching anything. I closed the hood.

 

Another update. I was able to change the knock sensor on the car yesterday. It didn't seem to cut out and I was hopeful that maybe my issue was resolved. I did a test drive and yeah, the car is still accelerating while my foot is NOT on the pedal. I again had to have my foot to the floor on the pedal to stop my car from surging forward. I thought as a quick test to see if the brake booster was bad was to turn on the car, push the brake all the way down wait a few minutes, turn off the car, and if the brake pushes back up at you, then you have a vacuum leak. I didn't get that but maybe I did it wrong. I have a smoke machine so that's the next project for this weekend. If I do have a vacuum leak on the brake booster, will the smoke test show that? Is there a spot I can connect my smoke machine to verify that? Edit: I'd also like to thank everyone who has been chiming in, you ALL have been helpful. I'm definitely learning a lot doing all this.

 

So I used my smoke generator and hooked it up to most vacuum ports. I didn't see anything. I'm at a complete loss. Maybe the brake booster has a vacuum leak but the engine works hard enough to maintain pressure despite the leak? I have one of those fancy OBD readers, is there something I should monitor while the car is running with my scanner to help me help narrow down the issue. I'm not pulling any codes besides the P1000 code since I keep disconnecting the battery when working on things.

 

So I dropped off the Focus at another mechanic (that has a great reputation in my area) and after he looked at it, he suggested taking it to the Ford dealer and have them flash the ECU. I'll be picking up the vehicle tomorrow. Should I try a Hail Mary and disconnect the battery and see if it the ECU will relearn? I still find it weird that was his advice because I think even with faulty programming, I wouldn't hear a relay clicking.

 

What is the RPM of the engine when the car is in neutral or park?

 

Usually, it hovers around 500-600 RPM which was the norm for it.

 

I was able to pull out the ECU and I took it apart to see if there might have been any moisture damage from the infamous cabin filter leak. No damage, no oxidation, nothing smelled burnt. I guess the next step is the stealership.

 

That sounds like it idles OK, but maybe a bit low. I'm wondering if it may be that when you put it in drive, the engine may move to much due to worn mounts. Maybe there is some issue with the throttle cable snagging on something and yanking the throttle open? It may even be that the shifting of the engine may cause a seemingly OK vacuum hose to flex and open up, and cause a vacuum leak.
If you have to push on the brakes hard to keep it from moving, and if it idles OK, that is a strange situation. I don't think a bad IAC valve would even cause that. Have you tried testing it with the throttle cables disconnected?

 

Yeah, mounts have been replaced more than once. Throttle cable has been checked as well. However, the weird thing is at park and neutral, the engine should stop shifting and not stall out if it were a case of the engine moving and pinching the vacuum hose. I have an appointment for Saturday but they're coming in a van to check it out tomorrow. I'll keep you all updated on the saga of the Focus.

 

Update, looks like there WAS a vacuum leak! Getting some other things checked out but no more acceleration.

 

I happened to see your post and read it all the way through! I have a 2003 5(door) can't remember the initials with it even after 21 years! I'm having a similar problem with surging. I thought my big feet were hitting the accelerator causing the RPM's to go up! I will have to ask my mechanic to check for a vacuum leak. The engine races when I put it in reverse - first time I drive it. The idly normally RPM's are usually 700 but if it acts like it wants to stall if I turn on my AC it'll idle fine - usually at 750-1000! I think I have several problems. Parts are hard to come by since Ford quit stocking parts on 2003. My mechanic had to make a part (thank heavens!) the last time I had issues with drive-ability. If it's too expensive to fix all problems I may be looking at a hybrid Maverick truck. I hope you find all your problems and they're an easy fix! I understand the emotional attachment to your car. My grandmother gave me her car (Tempo) and I kept that girl going as long as I could!

 

I had the same exact symptoms. You definitely have a vacuum leak somewhere. Mine did the exact same thing, I'd put it in reverse and it would surge. Once I pick up my car, I'll go over more specifics of what they fixed.

 

Well, what happened? I'm still having issues but as long as I have my a/c on it seems to drive OK. Once I get out of my garage (in reverse) it's not surging as much.