Started my conversion on my 1992 Mercruiser 5.7 350 reverse rotation motor Wednesday.

The motor was a carbed motor that ran fine after you rebuilt carb every couple of months.

Here my equipment.

1227747 ECM
O2 Sensor and Plate on exhaust elbow.
Fully Rebuilt TBI unit
All new sensors. ECT, TPS, IAC, MAP
NEW Wiring harness from PFISys
New Delco Distributor EST
New Coil
New Plugs and wires
New Electric Fuel Pump (SP1175)
2 10 Micron Filters one before fuel pump and after before tbi. Both New


Now here is the issue.

Cranks easily and starts easily only runs for a 2-4 seconds then dies.
Checked fuel pressure 15 psi at startup but wont stay running long enough to get pressure after start up.
checked all my voltages all are correct.
Distributor set TDC. with firing order 1-2-7-5-6-3-4-8

I feel that I am overlooking something or over thinking this problem.
Any suggestions are appreciated.

Thanks