intermitent no spark

[Fixit]

This one has been driving me nuts for awile....

This truck is a 1986 c10 half ton 2w drive with a 4.3 liter V-6 and a manual 3 speed on the tree transmission. It has a 4 barrel quadra-jet and electronic ignition.

Here we go... I'm driving around and it's running pretty good when all of a sudden the engine cuts out like someone flipped a switch. I coast off the road and wait a while then try starting it. It starts and runs like nothing was ever wrong with it. It tends to do this more when it is raining or the truck is wet.This problem continues to get worse. Now some times the truck will not start at all rain or shine (it always turns over fine) and it needs to sit a lot longer before it will start again.

I have had a mechanic that I trust look at this truck. He told me that it would not do this problem for him. I asked him if he got the truck wet. He told me that he actually put a hose on this truck for awhile and he also soaked the distributor and the truck just kept running even with all this water.
Like two days later the truck cuts out again at three in the morning in a commuter lot . Currently the truck is sitting in my driveway and I can't get this thing to start at all.

I have checked for spark and found none when this truck would not start. I do have 12 volts at the distributor with the ignition in start or run. I have replaced the entire distributor, rotor, cap, pickup coil, ignition coil in cap, spark module in the distributor and the plug wires. I have not changed the ECM yet. By the way this ECM has only 7 wires going to it and there is no ALDL connector under the dash and to the left of the column like on my 88 Suburban so I can not get any check codes.

If anyone out there knows what this is please give a yell. This has got to be one of the hardest problems I have come across and I'm getting sick of throughing parts at it.

When I was changing the above parts I also repaired a bad engine ground. Could this bad ground have messed up my ECM? Does anyone out there know how to test if this ECM is good? I'd like to know before I spend the 90 bucks that Napa is quoting me just to find out that I still have the same problem.