'94 F-150, 5.8L,Starts right up and seems normal at first but in about 30 seconds engine starts to run rough, idles very low and almost stalls and sometimes backfires but usually kicks in and revs but stays very rough. I have to stay on the pedal to keep it reving to prevent stall. After 5-10 minutes or so the problem goes away and it runs fine from then on.

 

I having somewhat of the same problem except mine is a 95 5.8 351W. Mine idles high and shifts hard into second gear. It also hesitates sometimes and like I'll go to accelerate on the highway as I am entering it and it will just like stop accelerating and I will have my foot to the floor.

 

Sounds like you need to clean your IAC (Idle Air Control) valve out with some throttle body cleaner. Mine's located on top of my throttle body, but I don't know about a 94 model. IAC valves tend to get carbon build-up on them after alot of miles and seize up. Spray it out really good, and take a q-tip to the hard to reach places.

If that doesn't work, you'll problably have to replace it. Mine did the same thing, but I got lucky. I cleaned it, problem solved.

 

mine did the same thing to me..went so far as to have it towed cause it wouldnt idle. The process of moving the vehicle apparently jarred it enough so that when it got to the repair shop, it idled normally. The guy at PEP Boys said, it's probably a IDLE AIr Control Valve and we can replace it for about 160.00, BUT....you can take it off, clean it with Carb cleaner yourself and it'll be fine. On a '99 it's a bear to get to with big hands, but accomplished it, and have never had a problem with it since...Dave

 

Well I took mine to my local ford dealership and had it put on a scope. The code came back as a throttle body sensor. $227 to replace it...It sucks because I have put about $400 in the motor department in the last 5 or so days. Bought new plugs and wires, altenator(it went bad the other day),and now a throttle body sensor. Man I'm going to have to get another job!LOL. Luckly that fixed it and it is running good agian(if not better) It is accelerating really fast now. The only thing I have noticed is the gas pedal is a little tighter or it is a little harder to step on it.