MPI kicks off when the car starts

I looked around on info regarding the mpi but have come across anyone with this situation yet. I have a 91 TSI I can't seem to figure out what's going on. I replaced the CAS and the ECU I have a 255lph fuel pump (currently stock harness) and the issue I'm having is I can start the car it'll run for 5 seconds ish but as soon as it start I hear the MPI kick out and cut the fuel pump.

The ecu passed all tests, CEL for 5 seconds, boost gauge 0s out, caps are all good - suggestions?

Thank you