Hey, fellas...bear with me as I am quite new to the Ford game.

I have a 1991 F150, 302, M5OD 5 speed, 4x4. I have been having this strange issue recently, and it is quite beyond me...here is what is going on.

Seems that about once a day, I could be driving along, everything is nice, idles right around 800 RPM, etc. Then, out of the blue, the idle jumps up to 1100 or 1200, and when I drive, between shifts the engine revs up to 2500 or 3000 and doesn't come back down for a few seconds. There is usually not a check engine light on when this happens, but I do have an intermittent C.E.L as well...my dad had this looked at before I was able to get the truck and the shop said it was not a big deal, but once I get back home (week or so) I will throw the scan tool on it to figure that issue out...but this high idle/revving between shifts has me stumped. If it happens, I just simply kill the engine, and re-start it and it seems that all is fine.

Anyone have any ideas? I am kinda/sorta thinking O2 sensor related, as it does not appear to have been changed ever (judging by the previous owner's maintenance record(s)) but I am relatively un-familiar with what a bad O2 sensor will do to an vehicle short of getting poor MPG (I am averaging 13 MPG by the way, in basically all types of driving. 302, 5 speed, 4x4, 3.73 (or so I calculated) gears and 235/75/R15 tires)

TIA

clean the throttle positioning sensor with carb cleaner. if that doesnt help id replace it. Same thing happened on my 93 302 5spd and cleaning it was a good quick fix for a couple months but then finally i had to replace the TPS

clean the throttle positioning sensor with carb cleaner. if that doesnt help id replace it. Same thing happened on my 93 302 5spd and cleaning it was a good quick fix for a couple months but then finally i had to replace the TPS

Forgive my newbness, but where's the TPS located on these engines? On the throttle body somewhere I would assume, just thinking I'd make sure I know.

Might wanna check the IAC also.

Might wanna check the IAC also.

Please expand IAC

Forgive my newbness, but where's the TPS located on these engines? On the throttle body somewhere I would assume, just thinking I'd make sure I know.

On the side of the throttle body opposite the lever and throttle cable.

http://www.partsamerica.com/ProductDetail.aspx?MfrCode=NIE&MfrPartNumber=FE1015&PartType=280&PTSet=A

Please expand IAC

Idle Air Control.

It's on the side of the intake.

http://www.partsamerica.com/ProductDetail.aspx?MfrCode=GPS&MfrPartNumber=77910025&PartType=757&PTSet=A

On the side of the throttle body opposite the lever and throttle cable.

http://www.partsamerica.com/ProductDetail.aspx?MfrCode=NIE&MfrPartNumber=FE1015&PartType=280&PTSet=A



Idle Air Control.

It's on the side of the intake.

http://www.partsamerica.com/ProductDetail.aspx?MfrCode=GPS&MfrPartNumber=77910025&PartType=757&PTSet=A


Thanks. Big help. What am I looking to 'check' with the IAC?