Truck gets squirrelly when it rains or is wet outside,wants to die after driving on 1994 Chevrolet 1500 Pickup

Wet weather makes the truck want to idle rough after driving on the highway @ 10 min, next stop causes truck to act as if it has a fuel pump problem(replaced already & filters), putting in neutral keeps it from stalling. Is it Ignition coil, camshaft/crankshaft position sensors, MAF/MAP, brake booster bleed, or fuel pressure regulator problem? I noticed bottom of front carburator's plastic housing small void by something with wires on it, so outside air could get in under the rubber housing gasket.

Asked by for the 1994 Chevrolet 1500 Pickup
While it is running as it should, spray wires, cap and coil with a 50/50 mix of isopropyl alcohol and water to see if problem returns. If it does a good tune up is needed. Check engine light on?
New distributer cap fixed it, however I could not get the old rotor off to put the new one on, is it rusted on? The old cap had white crystals approx. 1/2" long hanging from each contact and the alum. base was oxidized heavily. Any tips on getting the old rotor off or leave well enough alone?
I've had to break them off a number of times. Just grab the rotor with small channel-locks or big pliers and give it a twist. The rotor has a tab that engages in an angled slot in the top of the distributor shaft to hold its alignment. Once that breaks off of the rotor, the rotor will turn and then slide up off the shaft and that tab will comes right out of the shaft. This is one of those times you'll be worried about hurting something because you have to use more force than you like to, but the rotor will really come off pretty easy, its just too strong to do by hand.
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Have done the same things on a throttle body 5.7L and 7.5L nothing worked. Checked distributor stator, was rusty and nasty build-up. Would stall in gear, IAC count would drop to zero, etc. Changed distributor, (tired of replacing stators, dist is cheaper now days), everything went right back to normal, they are still running good.
Yep i agree, they give some problems, so much so that is almost needed in a good tune up on these vehicles! Something about the drain or vent in the bottom of the old ones thst gave some moisture problems, can't remember. (New dist. not a reman. OldTruckman.)
You know we must have gone to the same school, LOL
At least a couple of the same classes in that OLD SCHOOL! It still works though, cant get away from the basics! I dont care if they put 25 computers on them.
Yes, it is a 94 chevy 1500 2WD, 4.3 V6, has 230000 miles, I'm 3rd owner and have had it the longest, so the whole distributer should be replaced and not just an ignition coil or the cap, that's the kind of logical answer I was looking for, because I have had it towed to a garage twice and it cures itself, but they find other things that need fixing. A lot of the older mechanics around here are gone now. Thanks for the help.
You bet. These distributors are basicallly the same on all of the engines, just more or less cylinders. Thay do give a right smart of problems after that many miles. Tip, it needs to go back in the same position as the old one, if you swap it out. Look into sealing that hole you mentioned at the throttle body base also.
Everyone gets so caught up on the new, they forget what got them here.
See it all the time!! They never have set a set of points or adjusted a carb. never used a feeler gauge or dwell meter and most not even a timing light. While that seems like it is not important, it sure lays the ground work even for todays vehicles. They still work the same way! Just the delivery systems are different.
If wet weather makes a difference in how an engine is running, I usually expect to find a problem with secondary ignition components. (Coil, wires, cap, rotor, plugs).
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