sleeperZ2000

i need an engine wiring harness and new computer for my 2000 z/28 but it seems the only place i can find them is at my local dealer. i let a "friend do the free fan swith mod and some other stuff and he completely f'ed it up. for the computer it had a chip in when i got the car and when i pulled it out 3 of the little prong things came out with it. the car still runs but it misses and surges pretty bad.