GMC Repair: GMC Safari turns over but wont start sometimes, distributer cap, gmc safari

Question
I have 99 GMC Safari sometimes in the morning it will not start acts like not getting spark.Had to be towed to garage my mechanic replaced the cap and rotor after not being able to get an error code on the computer. This seem to take care of the problem until about a week ago. We had it towed back to garage the mechanic dried out the distributer cap and sealed it with silicone.This work until today wouldn't start  after about 20 min in store.about a half hour later it started. Seems to only happen when raining or humid.

Answer
Hi
There is 2 options for you. 1 would be to get a new distributor.
The second is to have your mechanic clean out all the corrosion in the distributor and to remove the EIP (External Ignition Protection ) screens that are located in the very bottom flat part of the distributor. These are VERY VERY small screens (smaller than the diameter of a pencil eraser) that may solve your problem of corrosion and condensation build up in the distributor.
This is Just a suggestion from experience,
I hope it helps
Good Luck
Paul