I just put my 2001 GTP back on the road. It was sitting for 2 years. Ran perfect when parked. The problem I have now is it won't accelerate without serious bucking. The gas is fresh, no check engine light or any other light is on. Runs fine at idle and low speeds. As soon as I try to go up a hill or pick up speed, it carries on like there is a bad plug or wire. Everything is brand new. Any help or advice would be appreciated.