2002 gtx 4 tec with 60+ hrs...at low speeds and rpm ski only runs on two cylinders. Pin it and once you get to about 30-35 mph the third cylinder will kick in. I've replaced all plugs several times with no change. Pulled fuel pump and replaced filters tonight (they were dirty, but I doubt this is the cause). Wondering what else I can check while it is in the driveway before the weekend. Coils? Injectors? Newby to 4strokes and skis, but comfortable with a wrench and two stroke sleds. Runs strong and is a blast once all three cylinders kick in, but a dog getting up to speed.