Sputtering at acceleration when warm

I need help diagnosing a problem thats driving me crazy.

93 Ski with 5.8 Pro Boss. When the boat is cold it will accelerate fine. Once its warmed up, say the second skier in, it sputters at hard acceleration, though it will ultimately get to speed and will run WOT just fine (no skips or misses).

I converted to mallory distributor about 3 years ago. I replaced the coil last year. I have checked the anti-siphon and fuel pick-up. I've replaced the fuel filter. It has a brand new carb. I pulled the manifolds and risers looking for obstructions and they are clean. Yesterday I noticed the back side of the resistor was broken, though I don't know how long its been like that, When it sputters, it doesn't seem like a transmission slip as it loses RPM's rather than gains them. Any thoughts out there? I've even had the dealer
work on it twice and they've missed it. (though I question just how thoroughly they water tested it because it happens to me every time.)

Thanks, Brian, I'll check that. Where did you get a bracket to mount it vertically?

Darren.
Ohm out the ballast resistor before buying a new one. Even though they are pretty inexpensive, there's no sense in replacing it if it's good. The same goes for the coil. Ohm out the primary winding to see if it's open (infinity). Good that the coil you have can be mounted in any position. There are plenty out there that are mounted horizontally!!

Thanks for the note, Pete. The Mallory conversion kit had a horizontal mount so thats what I'm dealing with now. Can you think of anything else it would be if its not the coil? Fuel or spark, right? And what more could I troubleshoot for fuel?

Its the PCM coil that came with the Mallory conversion from SkiDIM

Glad to hear you have it running again. Congrats on your new slalom skier!