Hoping someone may have had a similar issue and might be able to give a hand...purchased an original low mileage '87 Cherokee w/6 cyl 4.0L, auto, 4X4, meticulously maintained and running very well when I bought it. Started running poorly, but after a new full exhaust and new O2 snesor, it was running much better but the idle was way off - wouldn't stay running on it's own, kept stalling out. Checked all the vacuum lines and intake gaskets but all checked out, no leaks. Disconnected the ICS to find no change (idle still too low), so I pulled it and bought another one ($80). Once installed, it now idles smoothly but way too high. When I disconnect the new one, again no change (still too high). Checked the entire wiring harness from the ICS back to the firewall with an ohm-meter and all the wires are complete, no breaks, all show full reading. Any thoughts?? Thanks in advance~

Check the TPS.  One quick try is to clean the connectors going to it.  Did this on my dads 90 and it seems to have solved its having the same problem.

Other than that check out another group here called XJOG.  It is just a file repository.  In the files section there is a Renix injection manual.  Reading through that should give you some info.  The adjustment procedure for the TPS is also in that manual.

Andy

Hi. My 90 & my 87 also gave me the same problem and I replaced the idle control motor too. The parts manager told me to spray out the throttle body hole because they get very gummed up and can cause the motor to stick. i did that and have had no trouble since. Have a nice day. Steve

It sounds like your idle air control valve located on the back of throttle body near fire wall.