i rechecked and cant figure out why when i first crank my truck it idles up and down and shuts off most the time ....could the tps be bad and no engine codes

 

Typically, this is an indication of a problem with the Idle Air Control (IAC) solenoid. These were bad about gunking up in the late 80s, early 90s models.

Remedy is to remove the IAC and to clean the passageways and piston thoroughly with carb cleaner. Try to hold it so the cleaner won't drain into the solenoid.

Then again, it could've gone bad - not unheard of, but somewhat unusual.

A failed TPS will generally throw fits whenever you move the accelerator - the engine will tend to buck and snort. The engine will tend to level out and catch back up when the pedal is held constant.

Good luck, and keep us posted.

 

i checked the iac and its clean and looks new ...i notice if i cut ac on it cuts off at idle too , most the time i cut ac on after ive been on road and windows down to let hot air out ... i cranked truck let it warm up it cut off 2 times unplugged iac and idling dropped to 250 rpms....this is what i got from ford fuel injection ....This is really easy to test. First as with all problems you should gather the trouble-codes from the computer. Follow the codes for testing and repair. If you get a code that points to a problem with the IAB start the vehicle and bring the engine up to operating temperature. Allow the engine to idle without any driver input to the throttle or pedal. Go under the hood, and disconnect the electrical connector to the IAB. If the engine begins to stubble or stalls the IAB is functional and does not need to be repaired. If the engine idle does not change you should remove the IAB for inspection.