my car did this years ago when it started to idle realy low, it turned out that the idle screw had slipped causeing it to idle low which means that the oil pump isnt being turned over fast enough to make the right oil pressure. like you said when you rev the car it goes off, so try adjusting the idle screw so it idles at a nice 1000rpm and see if it still flickers, if it does then something isnt right. try this before you start worrying about piston rings ect . . mines been fine since and its been a good 3year since it happend.