I have a twin engine 32' Baja with 502's bored out to 509's. When I run the boat above 3500 rpms for about 5 minutes the port engine starts to show lower oil pressure than the starboard engine. When I come off the throttle and idle the port engine oil pressure drops down to 15 lbs. while the starboard shows 35 lbs. I already smoked an engine because of this problem, had it rebuilt, changed the oil pump, and still having the same problem. The engines start at the exact same pressure, the oil guages and sending units are new. When running the boat hard the headers and the oil filters feel exactly the same on both engines, and both engines run exactly the same water pressure. I'm stumped, anyone have any ideas????