brucet

Hi. I have a 95 XJ 4.0 auto and it idles too high... about 1500 rpm on start and 1200 rpm after a few minutes. The odd thing I noticed was that when the ambient temperature was very cold, 10 degrees or so it would idle down to about 900 rpms. Since the outdoor temperature has been warmer (30 deg or so) it doesn't get below 1200 rpms. It's almost as though the system is working backward relative to ambient temperature.

Iv'e searched and found a lot of suggestions that I've checked out including:
all vacuum lines
coolant temperature sensor
intake air sensor
intake/exhaust manifold gasket/bolts
TPS voltage
Map sensor
disassembled and cleaned IAC motor and throttle body
cleaned a harness grounds
checked alternator operating voltage
vapor recovery solenoid.

I'm kind of stumped here and don't want to just start "throwing parts at it" .
Any ideas?

THanks

Bruce