That could be causing the engine idle issues. Can't tell you how to fix it because I haven't had to but in those cases I go to this site which is pretty defining:
https://www.fixdapp.com/blog/p0122-code

As far as your temp gauge what is it reading at max? Are you seeing any over heating symptoms? Another thing about code errors. Even though your scan tool doesn't show a tripped code/codes it doesn't mean the PCM hasn't done so. Unless certain criteria are met the CEL won't come on and your scan won't read the code/codes. I'd take it somewhere and have it scanned.

 

I looked at the link you sent the difference with this is that the eough idle and low rpms dont start till the motor reaches 200 and my electric cooling fan doesn't kick in.

 

Your fan won't come on at 200. It doesn't come on until the temp gets to ~217 w/o the A/C on. With the A/C on it's controlled by a switch on the high pressure side. The normal operating temp of these 4.0's is 210 with a 195 thermostat.

You need to get the code problem taken care of. If you want some info you can start here:
https://www.cherokeeforum.com/search...archid=8268524

The idle and rpms are controlled by the IAC which is on the throttle body. You may want to go ahead and clean them as from what I've read on the TPS problem it should be done.
http://cruiser54.com/?p=60

 

Ok thanks for the help. As for the code I have tested the tps and it seems to be functioning perfectly. So I will update with what fixes it but I got to look into it further. As for the idle issue I will look into cleaning it. Thanks so much