Thought I would post this in the event it might help someone else if they mess up like I did.

Executive summary: Make sure the grounding strap from the head to the firewall isn't touching the bottom of the distributor.


The long story:
I have a 93 940 wagon. About two years ago, it started having some issues with not starting and stalling when it was rainy out. It ran perfectly when dry. This model has the distributor at the rear of the engine, right under the hood joint. I replaced distributor cap and rotor with new Bosch parts. Didn't really fix it so I replaced the plug wires and it ran without issues till recently.

This car is my daily 8 mile round trip driver but gets very few other miles so it has pretty much been sitting during the shutdown. We got a good rain a month ago and it wouldn't restart again. I eventually got it started and it was running ok. A day or two later, we had a very foggy morning with heavy dew- wouldn't start again. We had a pretty rainy week or two and I never got it running. I tried pulling distributor cap and manually drying a couple of times but no luck. The last week of so, I have been hitting it pretty hard checking things. I replaced the crank position sensor, the distributor cap and rotor looked good, etc. I cleaned up the coil contacts, tried swapping in my back up coil and ignition computers, etc. Nothing worked.

Yesterday, it finally dried off and the car started and ran perfectly. I hit the bottom of the distributor cap with some water and it died and wouldn't restart. Today, it started again and I did the same thing. After it dried, it restarted and I decided to feel around under the distributor to see what else might be there before I hit it with water. I discovered one of the grounding straps from the head to the fire wall was pulled tight across the bottom of the distributor. (there are straps from each side of the head to the firewall.) I worked to push it off and actually got a small shock from the spark. I put it back out of the way and it ran well. I can hit the distributor with a lot of water and either not kill it, or it falters and then catches itself, or it dies but it restarts in 2-3 tries.

I assume that I caused this problem. I have no idea when I did it. I've had the distributor cap off a few times 2 years ago and probably 2 times during this round. I could have done it at any point but this round of problems makes me think it has been a while.

I really appreciate the brickboard and all the info I was able to glean for troubleshooting this problem. Thought I should add this story to the knowledge base.