I have a 1996 f150 5.0 v8 that had been sitting for almost 2 years, it didn’t start at first but after I put new gas in and replaced the distributor and ignition coil It started but idles roughly at around 200-300 rpm and will stall if I dont give it gas every now and then. even at wide open throttle it only goes up to 400 rpm. I checked the fuel pressure and it has 40 psi. I’ve also replaced the fuel filter,fuel pressure regulator and cleaned the iac valve. Any suggestions?

 

Sounds like it is starving for air.
Make sure there are no restrictions like plugged intake passages or air filter.

 

Just checked and there doesn’t seem to be anything blocking the air but I pulled a p1507 (Idle Air Control Under Speed) so I think that my be part of the problem.

 

Don't buy anything. Remove the AIC solenoid from the throttle body. Clean the pintle of any accumulated carbon and the bore within the throttle body where it resides. Use a good carb or throttle body cleaner and an old nylon brush like a toothbrush to aid in cleaning if needed.Don't worry about any warning tags on the throttle body about cleaning it.This method won't harm anything. Also, DO NOT mess with the idle hard stop screw on the throttle lever. It is not meant to control the idle speed. Doing so will mess everything up. The computer is responsible for for controlling idle speed..