just to clarify...my gauge does go up and down in relation to startup,warming up, acceleration and so on,which i know is a quirk in our blazers. However, when i say my gauge is erratically moving i mean it will go back and forth very,very quickly between say 18-22 on the gauge when idling at a red light or stopped at a stop sign. sometimes it is steady as a bell at 20 when stopped. Dont seem to have any issues when in park.Could it be a bad ground and or connection. Bad gauge. Since the dist i hear drives the oil pump and correct me if i'm wrong,but would a worn dist gear cause this. Like i mentioned the oil pressure switch was changed several months ago to no avail. Is their another connection or sending unit that i can check. It is annoying as hell and i'm worried that this could lead into something more serious.