I have a 2000 XJ and as the colder months roll around I am starting to have idling issues (again). It will idle very low (200 to 400) and bounce around there, occasionally dying if I let it sit too long. Earlier in the year I was having the same issue, and I thought I resolved it when I replaced the tps and O2 sensors. Not sure why its happening again. Any ideas?

 

Clean the IAC and TB for starters. And clean all grounds and battery clamps until shiny.

 

X2 About the battery terminals & cables.