intermittent starting/running problem

This is gonna be a bit long-winded but I dunno what else to check:

2000 XJ Classic
4.6L stroker
stock ignition
~24lb injectors, fuel system otherwise stock (brand new fuel rail too)
800CCA battery, ~200A Ohio Generator alternator (both >1yr)
HESCO high-flow water pump & 3-core radiator, stock fans & thermostat

This all started around 3-4 weeks ago, when the weather (temporarily) got really hot (mid-80s to low-90s). I would start the Jeep in the morning with only a little hesitation (more turns required to get it started), then once running, it ran great. When I would turn it off however, it would need to sit before starting again (I thought initially I had vapor lock).

However, sometimes it would start up again <30min later, sometimes it would require several hours. Just about every time, it would take some work to get running. Sometimes "pumping" the gas pedal (a la carburetor) would help things along, but more often than not, it is just stuck not running for awhile.

I have a friend who is a Chrysler mechanic, he has access to the factory service manual & handheld scanner, etc. He is not able to "talk" to any of the modules (except the airbag module) w/ his handheld scanner, not at all. I do not have a check engine light, but the airbag light does turn on & off (suggesting a loose wire/bad ground/etc). This started around the same time as the starting issue. Also the cruise control doesn't work at all, and also started around the same time.

We have checked voltages on all the related wires from the PCM and everything appears fine. However, when the problem is prevalent, upon turning the ignition the starter engages, but there is no fuel pressure (confirmed by disconnecting the fuel line from the fuel rail). There also appears to be no spark, confirmed by pulling one plug along w/ the coil pack & touching the plug to ground while observing for spark. So, it's almost like the computer isn't telling things to turn on (ignition & fuel systems), even though the key is turned, and the starter engages!?

We are at our wits' ends in regard to what's going wrong, and how to fix it. I could wire the fuel pump relay directly to switched power, but then there's still the question of ignition.

Does anybody have any advice they can give me on this? I would certainly appreciate it, as I need a reliable Jeep not one that strands me sometimes for 30min and other times for up to 5hrs (or, even better yet, a Jeep that doesn't leave me stranded at all!).

Thanks a ton in advance.....

Oh and the factory repair manual says to replace the PCM next, but that is confirmed to work....also we tried a known good PCM from a 97 TJ 4cyl to see if his scanner would talk to it, but to no avail....

The cruise control problem began around the same time, it worked fine until 3-4 weeks agop & now doesn't work at all, but the wires all appear to be OK.

Bump

Did you replace the cam positioning sensor? It's on the bell housing. I have 3 XJ's 2 needed it replaced at about 150k to 200k miles!

Cam yes, the original one blew up (magnet tore to shreds), a few months ago. New one worked fine, still should be but may have trouble (have removed & inspected it several times). Also going to check the crank position sensor, it's possible it is malfunctioning (much more a royal pain).

It stalled on me while stopped at a light tonight, and required a tow from a friend after a little walk. Cam sensor wouldn't cause a stall, but crank sensor could, and could also prevent a restart. Maybe both, by some insane repeating coincidence (or perhaps not so coincidental, if they share any common power/ground/other connections).

We're still stumped about why the handheld scanner can't talk to the PCM though. We unplugged every single sensor, to mitigate the potential of a bad/faulty sensor causing a ground fault, and still couldn't talk to it. The PCM wasn't excessively hot tonight when it stalled, but this is by no means a scientific test to rule out the possibility my PCM needs replacement. However, it cannot be replaced unless the new computer can talk to the scanner - something no other PCM we've tried over the past couple weeks has done (we tried a '97 TJ, and also a '99 XJ, just to talk to the scanner, no starting/running even tried).

Besides the crank sensor, what else could be causing all this trouble? I don't have check engine lights, but that's no guarantee of anything, especially considering the PCM communication issues. Does anything else jump out? Any relay or anything?