1992 Ford Thunderbird lx 3.8l cel light/a.c

[Creoleswift]

Ok so I am stumped... I own a 1992 Ford Thunderbird 3.8l lx model and with 69,500 miles on it original. The other day I went down the freeway with my a.c on and as I accelerated to get on my check engine light popped on. The car had no hesitation or loss of power. But when I leveled out the rpm's 30 seconds later the cel light turns off. This only happens when I turn the a.c on and press the gas to go. I don't gun my car either just a easy take off every time. Now I have gunned the engine to see if it was and rpm or voltage fluctuation but to no avail it still popped on and few seconds later turned off. New gas cap new rotor.sparks.wires.tps.belt not slipping... pulleys are smooth no movement. . Please help...