Engine Doesn't Like Wet Weather

Situation:
My dad owns a 99.9% stock 91 S-10 Blazer Sport an he has a very annoying an big problem when driving in wet weather. After about 30 mins or so of driving the engine starts to studier an then just dies for no reason an won't start back up, but the weird thing is that after sitting for 5-10 mins starts right up with no problem, idles perfect like nothing happened but does the same thing again 30 mins later.

Question:
Anybody got any ideas of what could be wrong or what to do?


Some Truck Info:
Engine - 4.3L
Transmission - 4-Spd w/ OD Auto
Drive-Train - 4x4
Body Style - 2-Dr
Mileage - 150,000+
Other - Oil Filter Mounted 6" Behind Driver Side Headlamp Bought That Way

I haven't experienced this problem before, so all I can do is suggest that you run it til it stalls, then check for fuel and spark. If you can figure out which is missing, then there's a starting point for diagnosis.
 
Keep us updated and we'll see what we can come up with for suggestions.

Forgot to mention this in the original posting. The motor will turn over like it going to start but that's it.

ICM
Take it to your favorite autoparts store and have them test it. I think a new one is like $70. and makes sure you have plenty of grease between it and the bracket (heat sink) it attaches too. When it overheats it shuts down, it cools down and works normal, that is the sign just before total failure.

Thank for the replys guys but thanks to my brother the truck was totaled when warped it around a telephone pole so thanks but the truck is now sitting the junkyard so thanks