We have a 1989 jeep cherokee larado, 4.0 liter motor auto trans. that idles to fast. Idles at 1600 rpms in gear and 2000 rpms in park and idle. Have tried the idle stop and the throttle position sensor. What else can we try?

SOURCE: 97 Jeep grand cherokee 6 cyl. idles down to 0 and dies.

any leaks in intake or exhaust upstream of the sensors, sparkplug condition and engine controls/sensors for out of range operation (including fuel pressure and condition of regulator)
IAC should be cleaned and checked as this can cause poor idle and shut down. I'm not saying not to change O2 sensors, but unless everything else if OK, it probably won't help.

SOURCE: 1989 Jeep Idle Races at startup

yes its the iac "idle air control" they go bad also loose batt conections cause this problem good luck

SOURCE: jeep idles around 500 rpms

check throttle position sensor

SOURCE: 2004 jeep grand cherokee idling problem. Revs motor 200 to 500 rpms higher while driving.

I had the exact same problem on my 04 GC. I put some Techron Concentrate Plus Fuel System Cleaner in from Wal-Mart and it seemed to fix the problems right away. Let me know.

SOURCE: i have a 95 jeep grand cherokee that will

check the fuel pressure on the fuel pump