any sugestions on why my 00 jeep cherokee sport 4.0L 2wd has a rough idle sometimes?? I cleaned the IAC,TPS,and Throttle and sometimes it idles fine just under 1000 RPM and some other days its barely on 500RPM and hear a knock sound coming from like the bottom of the engine. The engine has died 2 times on me due to low rpm. crank and cam sensors were replaced by previous owner. I just bought this jeep 2 months ago!!!!!

 

Sorry to hear about the low idle, you might want to have someone with a diagnostic tool hook it up and look at all the sensor imputs and volts. This might show that the TPS is bad or some other problem exists. Also you can listen for vacuum leaks which might be throwing off the sensors and causing the idle problems. Look at the wireing harness for open/broken wires going to the sensors.