Mopar ECU Orange Box Strange Issues

OK, I'm stumped, wiring checks out. Runs fine(starts hard) with Orange ECU,
2 different CR109s from AutoZone, starts great, revs fine till 2500 then craps
out. Even disconnected from alternator after start and it craps out at 2500,
Added extra ground wire to ECU, reads almost 0 between - battery and ECU.
Is the CR109 the wrong ECU for this???? New ideas anyone???

you may have a 5 pin ecu with your 4 pin system. im not sure if it matters, 67Dart273 might chime in on this in a while.