U joints and radiator installed, engine was flushed and the truck runs great, but oil pressure is fluctuating from very low to normal with the throttle. No oil in the coolant or any other signs of a blown HG, no burning smell and no leaks. Hoping its just the oil pump which should have been replaced when we changed the gasket. This didn't start happening until the oil pump gasket was changed. Any ideas would as always be appreciated.