It doesn't idle bad. Slowly take the rpms up to 1,500 and the engine shakes very bad, you can feel it in the seat, and you hear a miss when you listen to the stacks. Once in a while the truck won't start it will just crank and crank and doesn't start, no service engine light or smoke out the stacks. Let off cranking, turn the key to off, then turn the key to start, and it will start every time. Today I pulled the chip out and ran the truck with out it. Truck runs great, I unplugged the icp and it ran better yet. Sounds like a whole different truck, no more knock,putt putt putt,miss or rattle. So kind of sounds like a chip problem. You think the chip is junk, pcm problem?