I've seen "MPG chips" advertised which only plug into the IAT on the vehicle... essentially an expensive resistor. I easily built an IAT fooler for my 01.5 CTD. Why not for other vehicles? If IAT is so critical (getting the onboard computer to lean out the mix) why not alter the vehicle's intake from a CAI (my 97 Cirrus intake snorkel pokes through the radiator support frame.) A simple alteration / baffle would have it sucking underhood air. Or go to an ITA fooler harness like the Cummins.
This is my daily driver & gets decent MPG in good weather but loses excessive miles in cold weather.
I have emailed Caspers again for an extension harness to start from for an IAT Fooler... I'd start with the same resistor as Cummins & think it would be close.