2003 Mazda Protege Power issue?

I was driving today a very short distance and this has never happened before, but on the way home it felt as if someone were hitting the brakes very hard for about a half a second, every 8 seconds or so. When I made the turn into the apartments all power cut off and the car was just drifting so I swung into my parking space.

I looked at the air intake and the filter was clean. No cracks on the intake hose. Battery wires are firm. Belts all in place. Temp at or below normal. I sat back down and put the key in and there was power again so I let the engine run for a minute and it didn't cut off. Now i'm kinda worried it's going to happen randomly and I have no idea what it could be.