Cyclical revving at idle

[traildog]

Been awhile since I was on this forum, but looking for some diagnostic help. My 4.0 has developed an idle problem, which I assumed to be a vacuum leak as it's had a few of those in the past. But the carb cleaner/propane test doesn't bump up the rpms and if I disconnect the IAC it dies immediately. I replaced the IAC for good measure to no avail.

This morning it was doing something interesting- idling at 2000 rpm, then every 5 seconds it would rev up to 2500 for a few seconds and then come back down. No input to gas pedal during this. It kept in this pattern for minutes so I took a video:

I guess next on the list is to clean the throttle body and MAF sensor. But maybe the cyclical revving indicates something in particular?

Appreciate any help.

 

[rusty ol ranger]

No check engine?

Id bet on a TPS

 

[traildog]

Hey I think that worked! Replaced the TPS and cleaned the MAF after work. Initially no change but after a cross town drive it seems the ECU adjusted parameters and it's running normal. Fingers crossed it holds. Thanks!

 

[traildog]

just for posterity this fix is holding 7 months later