Hey all, OSS here;

I have an issue that is sometime there, sometimes not. The truck sometimes seems like it's on cruise control, where it'll coast for a long time. Floor mat isn't making the pedal stick.

Sometimes at around 50km/h, my RPM's will drop to 1100 (foot off the pedal) It'll then sit there for a up to 15 seconds, then sometimes drop to 600 RPM for half a second, then bounce up to 1100 RPM, settle there, and repeat. It moves very quickly, like an electrical issue. I do go 4x4ing. Maybe just some mud/dirt stuck up on the TPS?

-OSS

 

Unless something goes really wrong inside the TPS sensor, it won't cause the throttle to hang. I would check the throttle body for smooth movement, that it isn't hanging up partially open. Clean the IAC valve. Check both the cruise & main throttle cables for smooth operation.

 

Also... I'd pull codes. See if there's any sensor failures stored.
And do a gentle wiggle/tug test on engine wiring harness and vacuum distribution. Had similar problem from a cracked plastic tee.

Off-roading also reminds of the vapor recovery system. Though a broken purge line shoulld throw a code, perhaps it's broken just right to give you this symptom.