When I kill my rig or nearly kill it it idles up to 2400 for a min or two and then slowly idles down. I've been told this may be a TPS issue? Opinions!?

 

Mine is an 88 renix injection and had simular issues I replaced the tps and it fixed my problem.

 

Sounds like a TPS (throttle Position Sensor) or IAC (Idle Air Control) issue. Both componants are located on the the front side of your throttle body on your 1990 RENIX 4.0 motor. The IAC plunger is the componant closest to the motor. Remove the 2 retaining screws and pull it out of its bore in the throttle body. Take a toothbrush and carbuerator cleaner and scrub the IAC and its bore. Re-intall it and see how she idles. If it's all good, great!! If the idle is still all jacked up, then most likely your TPS is junk.

 

X2 on that.... Clean carb or throttle body. I noticed more power and response plus a smoother idle after pulling of my TB and cleaning it all up new&shiney

 

Gunk keeps the butterfly valve from closing all the way and the sensors from operating as they should.