2001 Ranger 3.0L, 5 speed, 123xxx miles
Recently I have experienced the following after driving for more than an hour. When I stop the truck and let the revs drop to idle speed (~900 rpm) the oil pressure gauge flicks back and forth between middle pressure and low pressure. As soon as the revs are brought back up this stops.
When this happened initially I checked the oil right away but It was exactly where it had been when I had checked it the previous week. I noticed no change in the power, nor any suspicious noises, smells nor visible smoke. I also checked the coolant for signs on oil but saw none.

I have heard of problems with the oil pressure sensor in high mileage rangers. Does this resemble that problem or something else? Help me diagnose this please! Thanks

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2001 6cyl 3.0 2wd Manual Trans.