My Bronco Is Bucking, Why?

[Sorny]

As of lately my truck will start to buck and lower rpm's. When it does this I let my foot off the gas and try again it, usually it will do it about tree times then it will stop. What is causing this it only does it when the eninge is warm, also my truck has the up and down idle. Also when it is cool outside with lots of mostiure in the air it tends to idle low and sometimes stall.

 

[stinger]

efi ? it may be the throtlle position sensor

 

[Sorny]

Yeah its a 89 With the 302 EFI

 

[DragonDave]

Well at least for the up & down idle, try cleaning the throttle body & I believe the next culprit might be the IAC motor. Good Luck!