I have a real big problem and wanted to know if anyone could help me out. I just received my truck yesterday I had a 6.0 swap with a 4l80e tranny. The guy who did my swap says he completely swapped everything from the other truck, which is a 2000 chevy silverado 2500 and mine is a 1999 silverado. He says he changed the fusebox harness, tranny harness, he even changed my steering column. The problem is when it's in "Park" everything is fine, but as soon as I give it some gas in "Drive", everything electrical in my truck flickers on and off. Headlights and even gauge cluster? When I go full throttle the engine bogs. Everything electrical turns completely off for a while. I called the guy back, he said to bring it down to him and he'd take a look at it. Unfortunately I live in Pasadena, and he is in Humble so its kinda hard for me to drive it that far in its current condition.
EDIT: Actually any hard movements of the truck makes everything go off except the motor..which makes me feel even more like its a ground that is not grounded very well.