ok if your car is a key start car amd you swaped engine ecu. The car will start but then shut off after about 5 seconds.
If so you need to perform the ecu resync to security procedures in link below
No need to change VIN jist to the 30 minute resync proceedure
Also if the ecu you swapped in has a non standard tune, like for turbo or SC it might be set up for bigger injectors or different MAP sensor, the setup in ecu need to match the engine in car that may also be the problem
https://www.ft86club.com/forums/showthread.php?t=102810