A friend of mine has a 1997 Jeep Wrangler that he swapped a 4.3 Vortec from a 2001 Blazer. Lately, he has had an intermittent misfire affecting all cylinders, and on his way home today, he states that it misfired, then died while driving. He states that it almost tries to start, but just never does. I go look at this thing tomorrow, what should I look for?

The details:

Custom PCM, with tweaks, VATS programmed out, Emissions Programmed out, etc
He also has a stock PCM with VATS pulled, he has had that in for the last 2 days trying to get the PCM to throw codes to diagnose the misfire.
According to him, no codes are in the computer currently
He checked fuel pressure. It builds with key on, drops off, as it has always, and then when the fuel pump fires back up, it comes back up. Truck is not starting even with fuel pressure up.
He swapped ICM, coil (stock, and msd), etc, and the truck is still not starting. He is getting some pretty hefty spark, timing unknown.
He has the system that replaces the injection poppet system with straight injectors.

Ideas? It sounds like a fueling issue if I had to guess. He plans on putting the custom burn PCM back in the truck to see if it will start.

Check the vacuum hose on the fuel pressure regulator by removing it and smelling for gas. Once it builds up the fuel pressure should not be dropping when the pump is not running.

He found what the issue was. Turns out the bolts sheered off of the ignition rotor.

Wow..thanks for the update.