Stopped on the way home from getting smog tested (passed easily & ran great). Started up, engine idled fine for 10-20 secs. then started makeing loud top end noise and stalled. Removed valve cover, restarted. Noise immediatly, ran 5-10 secs. and stalled. No indication that oil is being supplied to top end. Dipstick reads full. I don't think it ran long enough to trip the low oil pressure light. Oil Pump failure??? If so, whats the drill for replacement and is it a "cheap date" if I "D.I.Y." it? Thanks in advance!