I've had a problem since I built the last 250, on the highway, it loses oil pressure around 2500RPM for a few miles. After years of putting up with it, I noticed it did it really bad once it got a little low on oil, and you could just tap the brake, without taking your foot off the gas (steady RPM) and the pressure would fluctuate, so I knew it was sucking air. I took the oil pump out, and sure enough, where the pick-up is brazed to the tube, there was a hole. New pick-up tube, and the condition is better, but it still has problems. I think there is a problem in the returns from the head, because I can kick it in neutral, or shut it off a second, and oil pressure is good for a few more miles. Motor is not sludged, so I was wondering if anyone knows of oil return mis-match problems. Gasket or holes?