Car surging? possible bad ignition box or coil?

[pfordamx]

i was curious about fuel thats one thing we did change. the car is on e85 and we always ran pump e that we mixed in the past and we swapped to a premixed with race gas e that we bought in 55 gallon drum i believe its renegade i tested it and it was 88 percent witch is fine. i didn't check check voltage at the box i'll do that today the car is on a 16 volt system and the in car volt meter was reading close to 17. oh and no alternator we just charge inbetween rounds.