I have a 99 truck with an 01 motor, 01 harness, 01ecm, and 01 pcm and it still doesnt run above 1500rpm. It still has the 99 pcm-to-ecm harness though. I noticed the 2 big connectors by the valve cover on the fire wall have different pinouts...just keep that in mind and dont end up with a mess like I have. Now ill be swapping pin positions to make this work (hopefully