2005 DodgeCaravan

My 2005 Grand Caravan runs terrible. It seems like it has no power. When I step on the gas it revs up to 4 amps or more but the power isn't there. If I gradually give it gas it will eventually get up to speed but I'm in trouble if I reach a hill. It chugs occasionally as I'm driving. The engine light was on but was turned off when I brought it to the dealer and had the air filter changed and the computer reflashed. I brought it back and was told by a mechanic as we took it for a drive that the reason for it running rough was probably due to the torque converter. When I took it in to get fixed at the same garage I was told they hooked it up to the computer and couldn't get an exact reading because the computer light was no longer on and until it came back on, I should just deal with it. HELP please