That does not sound like a transmission problem! That sounds like the throttle position sensor (TPS)! This sensor tells the engine management computer how much gas to shoot into the engine through the fuel injectors. These are not expensive to replace and do wear out. If your car has 100,000 miles or so on it this is what I would look at first. A decent mechanic can check this out very easily and it should cost less than $50 for the diagnosis.