[Gav]

Like Modena said, I would start again from scratch.
I have an LS1 ECU in mine which I sourced from a wrecker, after discovering the original ECU had an intermittent fault which killed the spark, I learned that many second hand ECU's on the market are actually repaired units that have been removed under warranty.
Yours, like my first one may unfortunately be a dud.

Rick, Zedn stated in the first post that the VATs (vehicle anti theft) had been removed.