Let me just start by saying I did check and it is a good oem ford iac for 1986 mustang. It was operating properly on the old a9l ecu but it does have that inline resistor right before the plug to the iac. So unless that resistor is effecting it I dont know why the ms3 goldbox isnt really communicating with it? I can get the car to start run and idle pretty smooth once it settles but im working out another issue. Reading like 75 to 80 degrees after idling for a long time like 30 plus minutes and car is very very warm like up to or above full operating temp. So I think sensor maybe bad or something skewing reading there causing rich running condition fooling ecu into thinking cars colder than it is... Car info is has a aem 30-4110 wideband calibrated to ecu. Tps is working and calibrated to ecu. Timing locked to distributor timing matched together when ecu in locked Timing. Afrs generally very rich around 11 to 12 flucuating alot at idle and under very light throttle drive around the block was like 10 to 12 afrs some 13s but very light throttle and low rpms. So im assuming the ecu seeing cold temps like 75 degrees from sensor is the rich running issue right now?