n.m.racer

I just finished my h/c swap on my 99 t/a. For some reason my mail order tune computer won't let my car run. It back fires when I try starting it and dies in like 10 seconds after it does start. While it runs the Tach shows no reading. I checked all connections everywhere and everything is hooked up right and no pinched wires and everything is plugged in. I swapped my stock computer back in and it runs and drives... But very rich and poorly.

I know it needs tuned but my question is does this sound like a hardware or software problem with the new tuned pcm. Was a table not imputed correctly? No security light is on the car. I've searched for 2 days but I can't find anything. My tuner I selected is extremely busy and hasn't had time to reply. I'm not saying who because he is respected on here and I do not want to give him any bad PR. Mechanically it runs strong and sounds healthy. I do not have any tune software so I cannot check. I have no ses lights or codes with the stock computer but it sucks to drive.

My mods are:
MTI stealth cam 2
799 heads
Ls6 intake
CAI intake
1 3/4 LT's
Built 4l60e
Trailblazer 4.2 converter

Any help or suggestions would be awesome.