I have a 1985 f150 with a 302 fuel injected motor, It doesn't seem to hold it's idle anymore, tried everything I could think of, anyone have suggestions? I even cleared all the error codes of the computer and replaced the O2 sensor.

 

Have you taken the throttle body apart and cleaned it up? Also clean out the idle air control valve. While you are doing this disconnect your battery to reset the computer. When you restart it you may experience some rough idle but just drive it for a while and it will settle back down once it relearns.

-Brian

 

I had this on my 92. Get a flashlight and take a close look at the intake manifold gasket. Sometimes they blow a section out and cause a major vacuum leak. Make sure the bolts are tight.

 

if the suggestions above dont fix the problem, have the vacuum system tested for leaks