1996 Jeep Cherokee Oil Pressure

Upon start the oil pressure gauge hesitates for a second, then reads about 40psi. Once running, the gauge flickers or bounces, and begins to drop. After a few minutes of driving between 20-40psi the gauge continues to flicker and drop, and drop significantly at idle (such as at a stop light). After several minutes of driving or stop/go traffic the gauge drops to 10-20 psi while on the throttle, and reads 0 at idle. If at idle and you tap the throttle, the gauge will jump and read 10-20 psi, then return to 0.

Dip stick reading is just below "safe" level, running 10W30, and there are just a few drops of oil on the pavement where I park.