I just bought this truck a few days ago. Someone tampered with the idle adjustment screw. It will surge at idle most of the time, every now and then it will idle just fine. It always surges on start up, and it doesn't matter if its in drive or park/neutral.

Here's what I did. The tps read 1.3v as set to where the previous owner had it. i know its supposed to be between .8 and .99, NOT over 1v. So i adjusted the screw back till it read .97v. Disconnected the battery, let it idle for a min. It would surge a few times, died once then stabilized. But everytime it starts it would surge till it died.

Realizing this isnt right I unplugged the IAC and screwed the screw out till it would idle on its own barely. TPS read 1.3v again. Took throttle body off, cleaned some gunk off where the egr comes in. Reamed out the tps holes to adjust it to be at .94v with the throttle where it is. Disconected battery, let it idle again. It doesn't stall now, idle seems high, and still surges randomly.

Now question time, i cleaned out the IAC. When i sprayed fluid on one side of the plunger the fluid was able to get to the other side. Is that normal??? If I did something wrong please point it out. I will be cleaning the egr out, if there was buildup outside it there is sure some in it too. I appriciate any help I can get, I am new to these fords

 

well, I cleaned the IAC again, found out the thermostat was stuck open (failsafe had failsafed). After i when through a warm up cycle it seems good. I still get a little fluctuation when i start it up bit but it levels out. My temp gauge now goes alittle past the cold mark. Are these gauges known to read bad? My temp and oil pressure both move but stay on the low side

 

Not sure what model you have, but my 93 with the 5.0 had the same symptom and it turned out to be the fuel pressure regulator mounted on the fuel injection fuel rail at the back of the engine.

 

mine's an 88, i'm going to check my fuel pressure once i find the adapter for my fuel pressure gauge for it... I have code 33 (egr) and a lean code so i figure the egr might be sticking open a little