Oil pressure drops to 0

I just bought a 99 dakota 5.9 liter, ran great for about 3 weeks, then all of the sudden after I had punched it and got moving pretty fast I slowed down and the check gauges light/buzzer came on and I noticed my oil pressure had droped to 0.I coasted for a second then it came back up, shruged it off and didn't think anything about it, about 2 days later it happened again (twice in one morning) so I checked my oil and there was NO oil on the dipstick, but I had changed the oil about 2 weeks before this happened and put 5 quarts in it, I know it didn't leak anything out, put a quart in it to get it home to be on the safe side, any clue on what could be going on? Oh also it does it sometimes going around the turn, buddy of mine told me it might be sending oil up to the engine but not back down into the oil pan.