Hi. I have a 95 4.0 Automatic. It idles at normal speed of about 800 RPM if the outside ambient temperature is below 20 deg F (even after the engine warms up) but if the outside ambient temperature is much above 20 deg it idles at about 1200 rpm. Yes I've checked for vacuum leaks, cleaned the ICV, checked all hose and connectors. Any thoughts are welcome.

Thanks

Bruce

 

sound like a airtemp sensor or pressure sensor is changing the idle have you checked for codes just because the cel light is not on does not mean there is a intermitent problem

 

https://www.cherokeeforum.com/f59/fault-codes-75472/

 

Thanks I'll check that out

 

Yeah, ussualy when you have an IAT stating a temp that isn't close to what it is outside it while cause you car/truck to have a bad air fuel ratio, replaced the sensor and see if it starts reading correctly.