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Oil pressure drops

I have a 1996 Dodge Ram p/u with V10 engine. when I step on the gas the oil pressure guage drops to the minimum in the range but when I take my foot off the accelerator it goes back up to the normal range. I recently had the oil changed and the crankcase is full.

You may have a clogged oil pick-up. Have the oil pressure confirmed with a mechanical gauge before digging further.

I saw this same problem on a Ford Ranger V6 I rebuilt. The oil pressure would drop as the truck drove along. The owner tried to correct the problem without dropping the oil pan as I suggested, but it finally threw a rod. After I pulled the engine, I found the oil pick-up screen was clogged with gunk that was so hard, I couldn’t chip it with a screwdriver. The oil pump was effectively trying to suck oil through a small straw, the pick-up was so constricted.

Have it checked with a mechanical gauge, as mentioned. Another possibility besides a clogged pickup screen is worn main bearings. When you accelerate, the torque on the loose bearings can allow significant leakage, dropping the oil pressure. Could also be a failing oil pump I think. The mechanical gauge will tell if you really have a problem. Also, if the pressure is normal or nearly normal when the engine is cold, it almost certainly indicates mechanical wear in the engine.