2013 prochem everest started sputtering today. Sputtering may not be the right word, maybe skipping would be more accurate. It's only every few seconds but would get progressively worse until I finally shut it down. When I tried to turn the key I had nothing. Few seconds later i was able to start it back up, ran fine for a short while then the same thing started over again. I managed to finish my job I was on but now I'm back at the shop and don't know where to start. Any clues?