hello england, welcome to df.
below is a pic of the IAC. as Charlie said, its on the rear of the throttle body. the pintle fits into an air passage and moves in/out under PCM control. do not push/pull/twist on the pintle or you'll break it. clean the pintle and air well of gunk. also clean out the small air port in the center of the well.

Good suggestions guys - it gives me some things to check.

Actually; (At least the aftermarket one's) are adjustable; You pull back on the pictured Black part, then you turn the tip either right/left to adjust it out more or in more.. don't go out too far else you'll cause serious damage; but I found if you want to raise your RPM (I did it to 750) it really helps your git up.. but cons would be consume more gas at idle... and higher temps at idle. vs the 550/600 setting.

Erm, does that actually work? It was my understanding that the PCM (after being reset) would run the pintle all the way out, to "re-find" it's fully closed position, and then would take it from there to maintain programmed idle speeds and such.

im having the same problem now i am lost. i have donethe plenum gasket fuel pump distributor cam and crank sensor the rotor button cap plugs wires ignition coil IAC valve. i cant get it to run right even pressing the throttle till it gets to operating temp but i have to fight it to get there once there in runs perfect. One thing that got me was when i tried to re sync everything it wouldnt let me some error came up and said it could not be done. i just want it fixed been down for three months now

Check for vacuum leaks. Also, add your truck info to your sig, and profile.

Just a thought, but check out the 02's and catalytic converter. Clogged up cat, could cause some running issues.

the cat is gutted

I had the same problem. It the the air in take with cleaner and then do a sea foam treatment. Good Luck.