Just today when rpms go up, oil pressure goes down... is my oil pump going out? 1991 Dakota v8 4w drive.

Nothing wrong with that, your oil pump is geared to the crank shaft. The higher the revs the more oil is being pumped by the oil pump. The oil galleries are a fixed size so as the flow increases the pressure rises to force the increased flow through the same size oil galleries. You should also notice that you oil pressure is 10 to 20 psi higher when the engine is first started and every thing is cold.

as you step on the gas the rpms go up ,the oil pump rpms also go up ,the faster the oil pump turns ,the more oil pressure you will have.

Oh man, I had the same problem with a Chev Baretta. Domestic autos of those years have so many redundant systems to prevent ruining the engine. In the case of Chev, low oil pressure would shut off the fuel pump. But a bad oil pressure sensor will do the same thing, as it's giving a false pressure reading. Best advice is to get your hands on a Chiltons/Haynes repair manual for your truck and follow the trouble shooting section. Best of luck. (After much frustration I did get that sensor replaced. Drove great until the fuel pump itself quit. I left that repair to someone else. I'm not into self-immolation.)

have a mechanic test the oil pressure with a mechanical gauge
it is more than likely that the electric sender unit has failed and is sticking internally
the tic noise could be a relay working from an intermittent power supply or bad ground

Might be a bad Oil pressure sensor or a weak oil pump and when the car idles the pump even if it spins but the power is low but after you push the Gas then the RPMS goes up and the pump spins fast the pressure gets higher. Good luck

Sounds to me like your oil pump is bad, not pumping sufficient oil at low RPM's. If the gauge shows pressure when driving or revved, the sending unit is working

I personally would try pouring a bottle of Berryman's B-12 in the crankcase when it is warm and then changing the oil (which you have tried a similar approach with the flush). Or, I would add approx. 8 ounces of Sea Foam engine additive to the crankcase and drive it around for a little while to see if it helps. As a side note: You don't have to change the oil with the Sea Foam, only the B-12

Your sensor may be faulty or your oil pump is faulty

It could just be your oil filter.
But most likely a weak pump, or a clogged pickup screen in the oil pan

The oil pump is in the pan at the bottom of the distributor.