When I push in my clutch my oil pressure drops to almost nothing on 1997 Ford Ranger

With it sitting idle oil gauge jumps up and down

3 answers
could be a faulty guage, oil pressure sensor, low oil level or wiring issue..
Agree with above, check oil level first. Just remember... You have a gauge but the sender is actually a switch, just on and off. The gauge is either up or down on this vehicle it does not reflect actual pressure changes (why Ford did this I don't know). If the oil level is OK I would have the oil pressure tested by someone.
AGREE WITH BOYH 1&2