Another plot twist. Plugged a friend's wireless scanner into the van this afternoon, and with the key turned to On, the relay clicks and fuel pump primes every 15 seconds. CEL blinks once each time. This is the same exact symptom I see / hear when the van stalls when warm. I normally use corded , which does NOT recreate the relay click and fuel pump prime every 15 seconds symptom. Also, could not get the ELM327 to connect to the vehicle for error codes, etc.

Ghosts? Pirates?

 

In that case, I suspect your ASD relay is dropping out either because it's failing, or the new PCM is faulty. Is the PCM a brand new one, or reconditioned?

 

That makes sense. I've swapped the ASD relay with other units from the van, and a brand new one. No change.

PCM is remanufactured. I can't find a place that sells new ones for a 2000 van. So far I've been through 4 different PCMs, each of which had it's own stalling issues (P0505, No Bus, idle stall at 80*C).

But how the heck does plugging in a bluetooth OBD II scan tool effect this? Relay drops off every 15 seconds with the ELM327 plugged in. Insane!

 

So I'm not sure how to test the Ignition switch. But I can say I had nasty stall symptoms while driving and replaced everything from plugs wires, rotor, cap and coil. All of that made it run slightly better and symptoms went away for a few miles but they came back shortly after. It ended up being my ignition switch. It's easy to replace and fairly cheap. I would just buy a new one and clean up battery connections. It solved my stalling issue.
my van would stall when driving like a continuous die/revive episodes and got worse over time. Then it would die, sometimes not start up right away. Sometimes it would start up immediately after. It all started off with lack of power like fuel pump was going out. Essentially I guess the pcm sends the signal thru your ignition switch -> coil -> spark plugs. The issue lies in the ignition switch where it's unable to send the spark. Sounds confusing but I would suggest just skipping the testing part. Swap the switch out with brand new one. Pretty sure it will fix your stall.

 

This is the switch

 

The only thing I can think of is, the plug-in unit is drawing its power from the PCM, while a handheld scanner has batteries for power.

 

If you have the P0505 code with 4 pcm's it's not the pcm. Need to look into the wiring/plugs from the pcm to the iac. If the pcm can't work the idle motor it will stall.

 

Thanks Moparite. But I do NOT have the P0505 error with 4 PCMs. I had P0505 with one single PCM, the original unit that the van came with. Have not seen a P0505 error in any of the 3 new or repaired units.