Why does 2002 Jeep Grand Cherokee oil pressure increase with acceleration drops when idle?

Oil pressure is basically the

Pressure when oil is forced through vital engine components such as camshaft bearings and other bearings.

Due to the enormous stress in a combustion engine, normal ball bearings cannot be used, thuss oil is forced in between the layers of bearing rings. This way, oil functions as the bearing force.

When you accelerate, the rpm increases and the oil pump also increases it's rate of function. This leads to a raised oil pressure, on the gauge it shouldn't rise more than a bar, two at most.

You might experience higher oil pressure when the engine is cold, due to the increased viscosity of the oil.