I have a 94 f150 with the 5.8. It was idling rough and would sometimes die. I replaced the throttle position sensor and it was running much better but would pulse between about 700 and 1100rpms. I then decided to clean the idle air control valve. That didn't seem to make any difference but when I revved the truck, it stayed between 1500 and 2000 rpms. I replaced the IAC valve with a new one and there was no change. I've tried shutting the truck off, and unhooking the battery for a few seconds but still runs at 2000rpms when started again. Anyone know what might be causing this?

 

Possibly your new Throttle Position Sensor is bad. Where did you get it?

 

Pull your codes? It will give you a place to start looking instead of throwing parts at it.

 

This sounds probable to me... Do you have a friend who has a similar truck you can test your new TPS on?

 

I believe you are correct. I removed the TPS and found that it was sticking. I will be replacing it tomorrow.

 

Just curious, where did you get the TPS?

 

I bought it at Carquest. Short of the dealerships Carquest and Napa are the best part stores we have around here. It's hard to pay dealership prices.

 

I had the same problem and had the same answers everywhere with no luck in fixing it. I changed my IAC, went through 2 TPS', cleaned my throttle body and no change. Finally, I messed with the throttle stop screw located on top of the throttle body. It closed the plates enough to bring down the rpms and run fine and actually brought my gas mileage back up. This was last case resort. Check everything twice then run your truck while adjusting this to watch the rpms return to normal.