[89IROC&RS]

however if it was what i said, it would happen at a consant speed, not just accelleration. so is it only while accelerating, or is it when you are cruising?

other than that, check your trans fluid level, color, and smell, (not taste lol) if its low, brown, or smells burned, you need a tranny service.

also, have you done any modifications to the drivetrain, such as a higher stall converter, aftermarket rear gears etc. etc.