Please help! I have a 99 jimmy sle with 4.3 I can start it up it will idle around 13 rpm in park. When I drive it I don't need to push on the gas, because it will pick up speed and and shift by itself. I guess this is kinda like autopilot in a way.

sounds like you may have a problem with the gas pedal or with the fuel injection system

do you know what all in the injection system could cause this??? I put a new tps sensor on it and it did not help.

no i dont but you should have a mechanic check it out

I got it fixed. The throttle body had a sensor on the back of it that was bad