EPC light keeps going on an off on my 99 Beetle. on 1999 Volkswagen Beetle

I have a 99 VW Beetle that the EPC light keeps going on and off. When this occurs the car starts jerking and looses power. It also causes the the car to quit and has a hard time starting again. I have hooked a computer up to it and no codes came up. You never know when this is going to occur. One minute it will run great and the next minute it runs terrible.

have codes scanned and post so we can adv