I've had an issue with my 2006 Focus ZX4 automatic running rough at idle, idling low, and even cutting off at idle. I've compensated for this by keeping my foot in the gas while idling(dangerous with it in P or N). I've been putting off a fix, both because I've been broke and because I'm not certain of the issue. This has also been accompanied with the Check Engine light being on.
With that being said, about a week ago I noticed that the throttle was sticking open, to the point of having to ride the brake going down the road to keep from speeding. This past Tuesday on the way home from work, it started as it has been(low/rough idle). After about 5 minutes of driving, while entering an Interstate, while accelerating to merge with traffic, the throttle seems to have took off by itself. The gas pedal was on the floor and the car was accelerating out of control(other than braking). I immediately pulled over, putting the trans in neutral. The engine revved to what I can only assume was about 3500 or 4000 RPM(no tach). Of course, I immediately shut the engine down. After a few minutes of weighing my options(towing or driving), I decided that I couldn't leave it sitting on the side of a busy Interstate. I started the engine, again resulting in revving out of control. I instantly put the car in gear(I should be impressed with the hole shot that my little Focus pulled...50 yards). While driving on the Interstate, I was riding the brake to keep the car under 85mph.
I exited the Interstate, having to STAND on the brake with both feet while pushing on the back of the seat(only reduced the speed to 10mph). A bit of offensive driving(I was quite impressed with my skills) to avoid having to come to a complete stop allowed me to avoid further damages. Long story short...I was able to get it home without killing myself or anyone else(may not have been the case had it been my girlfriend driving). I simply pointed it at a parking spot and killed the engine.
When I checked out the throttle body, the throttle was sticking. I removed the throttle body. Butterfly was black with carbon and other grime. Cleaned it with carb cleaner and a toothbrush. Replaced it and reconnected the battery(disconnected to get Engine light to go off). I started the engine and it didn't rev high. It was back to the low/rough idle from before. The Check Engine light is off now, but I haven't ran the engine for very long at all.
I have not yet road tested the vehicle, for fear that the throttle will stick wide open again and I won't be as fortunate as I was the other day.
It is worth saying that, when I disconnected the throttle cable from the throttle body, it won't move very much when manipulated by hand. I'm unsure if it is supposed to have several inches of movement. It had about 1/2" - 1" of movement. It did, however, retract itself when I pulled it outward.
I apologize for the long, rambling story. I'd rather give too much info than to not give enough.
I suppose my question is three-fold. Will a clogged Catalytic Converter cause it to run rough, low idle, and stall at an idle(hesitate slightly at highway speeds also...even with the cruise set)?
Second, could this idling issue be caused by the filthy throttle body?
Third, is it possible that the throttle body cable needs to be replaced(reference the "stuck wide open and nearly killed a hundred people" issue)?
I will give it a short road test soon(gotta go to the grocery store cuz I still have to eat). Will comment on this post when I return with the results of the test(pray for me...there are 2 stop lights and a stop sign between home and the store).