If it is just a stock engine I'd buy a harness and ECM from someone who cleans up OEM harnesses. Or send them the ECU that you have and get an OEM harness modified to work with it. you can potentially send your ECU and harness to have them verify that everything should play nice. You can spend weeks chasing electrical or pay someone a couple hundred to do it for you.

something i've seen more than once on LS swaps is someone will put the harness ground to the bell housing of the transmission instead of the back of the cylinder head. dirty grounds cause all kinds of goofy ****.

 

Thats what i been doing now for awhile. Get rid of all the GM workarounds in the stock PCMs. haha

 

yes it did run but was injecting one port and would smoke and shut off . it had a 4cl ecu thats why i chenged ecu

 

4 cylinder ecu