The first 10-15 mins. it runs great, but then it will stall, jerk, and die when I brake or stop completely. To keep it running I have to slip it into neutral while stopped, and slip it back into drive when I need to take off. It jerks a little when I take off too. The spark plugs and wires are fine, and the coil pack was replaced, so I don't know if the timing is off or what. Please help I need to fix it ASAP!