My SVT very suddenly started to run like crap. Here's the situation. Filled up with gas today. Car has been running quite well, got 29 mpg on the tank on a 250 mile trip. On the way home, a few miles from the gas station the car starts to lose power and runs really rough in gear or neutral. Sounds like rocks rolling around when I apply throttle, gargley and deep sounding. I coast to a stop in neutral, with the car stumbling the whole time. Shut it off. Turn back on and it can barely idle, requires throttle to keep from stalling. Runs terrible, sounds dangerous even. Shut it off. Called AAA and had it towed to my local shop. It's sitting at the repair shop for them to diagnose tomorrow. No CEL through any of this.
Hopefully its something simple, I'm suspecting fuel filter or pump... Better not be timing related since that was done 55k miles ago.
Car has 135k miles.
Fuel filter mileage unknown, could be quite old as the filter, bracket, and nuts are very rusted. (Which is why I haven't gotten to it.) No mention of it being changed by PO, who kept decent notes and was a Ford mechanic.
For past few months car has had a slight stumble at cruising speeds and occasionally threw P0133 and P0172. Changed O2 sensor, reset ECU, car has run much better since with no codes, but still not 100.0%.
Has Toms Tune. No issues with the tune AFAIK.
New Motorcraft copper plugs and CFM wires.
Basically, I'll see what the shop has to say tomorrow, but I'll back up their thoughts with what the FF community has to say.
UPDATE WITH RESOLUTION:
It was bad gas. Really.
Shop replaced the fuel pump and filter. Still ran like garbage, very difficult to start it. Sat for a few weeks in the cold. Tom (1turbofocus) helped me get it started and debugged. I got the car running with the gas on intake trick. Once it was warm it ran ok, but felt down on power, like 50%. Figuring it might just be as simple as bad gas, I put some Heet and Seafoam in the tank and tried to drive it off. Put 100 miles on and it ran better as it went, almost completely back to normal. Still had a small hiccup between 1500 and 2500 rpms, usually in second gear. Filled it up with gas again and let it sit overnight in the cold. It fired right up the next morning. Ran better and better over the next few days, and no issues since. Boo Citgo!