problem solving engine trouble

Ok. I have a new coil ordered.    I'll get the rotor and cap cleaned up and double check the wiring once the coil comes in. Hopefully my problem is with the coil.    How do you know what coil will work with the e spark?    The coil currently on the boat is a C819 (autozone).

What type of rotor and shutter do you have with the e spark?    I've cleaned up the old rotor and was ready to install it but wanted to make sure this setup was even correct.    

I spent a full day on the lake Saturday with two guys that know a lot more about engines than I do. Here is what we found out.

1) All the spark plugs were black and we found one that wasn't firing. We went ahead and changed them all out.
2) We double checked the timing advance and it seemed to be advancing fine.   The weights and springs move freely and we reved the engine up to make sure it wasn't getting hung up anywhere.
3) We played with different timing settings and actually found that the main problem we've been having (stuttering under load) completely went away when we changed the timing to top dead center (or set at 0 degrees).    The only problem with that is we were not getting as much power out of the gate with that setting. It was noticeably sluggish to get up on plane.     When we brought the timing back to 10 BTDC it had plenty of power but the problem returned.
4) We put a new coil and distributor cap on which didn't change anything.
5) We checked for vacuum leaks again by spraying around the carb but there were none that we could find.    We removed the carburetor and changed both gaskets to thicker gasket material just to be safe.    Everything was flat and clean and there were no signs of a vacuum leak.
6) While we had the carb off we decided to change the jets back down to a smaller jet size since we knew we were running rich anyway. The carb came with 67 jets so we went down to 65 jets.   After we did this we found that we could get the timing set to around 6 BTDC without having the problem occur and very little power loss out of the gate.   a definite improvement.
7) So we left the lake on saturday with the boat running pretty well overall but the timing is set to around 6 BTDC. I ordered 63 jets so I could try that size to see if we could get the timing set to 10 BTDC without losing power or having that stutter under load.

looks like we've finally made some progress.     Any other thoughts based on this info?

Glad you are making progress. If you have black plugs it is rich, does not sound like a vacuum leak. You are on the right track.
It does sound like your distributor advance springs may be letting the advance come in too soon. Are stiffer springs available for this distributor?