Ford Repair: 1997 Ford Ranger transmission, clutch system, moisture sensor

Question
1997 Ford Ranger 5sp,4cyl 110k mi.ext.cab.2X2.
When it rains, either garaged or not, initial start after hours of non-use, transmission will not engage. If I let clutch out, it acts like it will kill engine. After running thru all gears pushing clutch out/in until it finally CLUNKS into gear, in reverse it moans loadly and moves with resistance (like brake still on). A friend mentioned it might be some type of moisture sensor as a guess. This has done this since i bought truck w/70k mi on it 4 yrs ago and is getting progressively worse. No rain, no problem! Other than this, truck has been bullet proof.
Thank-you for your time.

Answer
Hello and thanks for the question...I'll try to help.
I've NEVER heard of any "moisture sensor" for a clutch system. I would how ever take a look in to replacing the clutch. OR at the very least pull the transmission out and look at what is going on in there.
Hope this helps,
Erik