Speratic Idle issues.

1990 4.0 Cherokee Limited.
Is there a throttle position sensor for this year Cherokee?
Here is my problem,
When I start it up, it spits and shutters at idle until I give it gas then its ok, but when I let it go back to idle, it does its jitter bug dance.
Other times, the idle goes to a high rpm and it wont come down until I shut it off and let it sit.
Is it terminal? Hasta

Time for a little maintenance.

Bookmark this website: http://www.lunghd.com/Tech_Articles/Engine/Basic_Sensors_Diagnostics.htm

Clean the throttle body and IAC (idle air controller) port; clean the IAC pintle--be careful, they can break.

The IAC controls idle speed by executing extend/retract signals from the ECU.

You want an idle of 700~750 rpm after the engine and transmission (auto) are fully warmed up, after about 20 minutes of operation. For an auto you need a spare set of hands to apply the service brakes as the idle speed is checked in DRIVE.

As the Renix is real-time only there is often an initial rise in idle on start--the ECU stores no information--as the ECU figures out what state the engine is in and adjusts the IAC.

IACs don't fail that often, unlike the TPS, but they can become "lazy". Next time you are at the salvage yard try and grab a couple from other Renix years, odds are you will end up with a good spare.