Has anyone out there had this probem. 91 factory oil pressure gage reads "straight across" at idle, all is good. When driving down road and giving it throttle, the gage starts to drop. I let off and it goes back to normal. Yeah I know I should have the aftermarket gages in by now but I just haven't got to it yet. I have seen sending units go out before but this is a new one to me. WTF?