[98SteedaGT]

My car did the exact thing right after I installed U/D pulley, T/A, and MAF on my 4.6 -- The computer light came on for a few minutes at first while it was re-learning the fuel/spark for the new MAF, but it went off after a few minutes... Then about a week later I was cruising around on a highway right about 55 or so, and the CEL light just came on, after a few days it went off. Came back on a week or so later, then went off after I cleared the ECU. I had autozone read the DTC on it and they said my Left Rear HO2S was bad, but it really wasn't... I install the MIL Elims in my car, it didn't solve anything at all, it did the same CEL on/off for a few more weeks, then one time I cleared it and it hasn't come back since. I guess the ECU got tired of fighting me and just learned to play nice with the new parts (hehe). Anyways, I didn't notice any difference with the MIL's and they didn't really do anything, since the light came back on and off... I do have to run 93 octane only!, if I run anything lower than that, I get the HO2S failure again.... I don't know about your car though, I think the new GT's run a differnt code set or something, I know you can access your DTC through the dash gauges (if you have LED read out), I don' t think you can do it on the all analog types...