cannot get this engine to run

Tried to fire this engine up and cant get it to run. It seems like it wants to but just not there. I had everything out as you can tell by the resto thread and I hate this. It is getting fire and it is getting fuel. The timing is right. I checked the schematic and it seems like the wiring is right. I just sent Tyler down to get a ballast resistor and a new ECM. Plugs are new and gapped right. Coil is hooked up right. It starts to run just a little and stops. it is doing some backfiring out the carb. I have moved the dist. all over and still not firing. Engine is grounded and so is the ECM.Anybody have any suggestions. I am tired and apparently missed something here.

check and make sure the wires run and start from the key switch are right it will start and run if there not right but as soon as you leave off the key you stop getting power to the run wire from the switch

just an Idea had it happen to me