Car starts, then immediately dies. Help, please...
 

1994 miata. Bought the car not running. pulled the old engine out and replaced it with a lower mileage engine. Go to start the car and it starts, revs to about 1k, then immediately dies. Every time. If you push the gas pedal any at all before start up, the car will rev accordingly, but still dies at the 1k mark or so. Ive replaced the coilpacks, pump, fpr, fuel filter, maf, injectors, and ecu in an attempt to cover all bases. Still nothing. Out of a bit of curiousity, I pulled the DIYPNP out of the turbo car and threw it in. Fired right up. Any ideas as to what I may be missing? Thanks in advance.

Idle valve.

Replaced the IAC with a spare. Same results. Crank, start, rev to 1k, dies immediately. Fires every time with the same results.