i installed 42's and 2.9 and got a trifecta tune and now my car wont start id did for a bit and it idled really rough and shut off now it wont start at all. i used the old harness is this aloud does it not give it enough power im throwing a fuel pump primary circuit code now

 

Check fuse for fuel pump, and all fuses for that matter. You could have shorted something when you swapped ECM's (assuming that's what you did).

 

How long did the car run for b4 it shut off and does the security light stay on?

 

fixed aparently gm made 3 rows and only 2 rows can be used for the fuel pump relay so yea im good and the cold air came loose thats why it was rough idle