2000 Grand Prix intermittent no start and dies randomly

[TheDarkAngel]

Needing help here, as I'm completely stumped. I have a 2000 Grand Prix, that I swapped a Park Ave Ultra L67 into, and now I'm having mega problems. Got a custom time from intense made, albeit for a top swap, but I didn't think it would cause any problems. Ran tests for spark and fuel pressure at the rail, and it passed both. When it doesn't start, it backfires, so I know it's getting fuel. When it does start, it runs like garbage for the first ~3 minutes, then smooths out and purrs like a kitten. Get out onto the highway, and all is fine, until it randomly dies. Typically dies ~5 times on my 25 mile trip to college. Replaced the crank sensor, MAF, did a re-learn, and nothing has helped. Either need this car to run, or I need someone to buy a car with these issues. Open to suggestions.

 

[BoostedPontiac]

When it dies, does it start back up or does it need to cool down a bit?

And codes?

 

[TheDarkAngel]

When it dies, does it start back up or does it need to cool down a bit?

And codes?

It it will start back up and run fine, after about 30 seconds to a minute with the key off. Until it dies again, then the same thing over again.