Hey guys, I had the exact same issue. I worked on it just about every day and replaced a ton of parts spending a bunch of money for about a month and a half. When I put it back together that last time that solved the issue I made a few changes which any could have been it but I believe it ended being the fuel selector. the Nob that you select between your main feed or your reserve line. Since removing that I have never had a single issue with the ski and still trailer with me riding so when my other ski acts up, old reliable is sitting there waiting.
But also check your carb/ intake gaskets, compression, tunning, plugs, trim spark plug wires back, and you oil-fuel ratio I had to lean the oil out a bit on min to be right.