In desperate need of direction on troubleshooting my V135 carbed 2 stroke 1989 model year with 40 Amp stator. I own the factory manual and a DVA meter. Do not have a timing light but am willing to get one. Below is the recent history.

Summer 2020: At the beginning of the year motor was running fine started to run hot in the no wake zone but we didn't have time to do the impeller so we ran it like that and kept an eye on the temps. It never overheated. It did start to develope an issue where it would radomly have reduced RPM at high throttle even sometimes starting out at reduced RPM then all of a sudden start running with full rpm. The impeller was changed and the overheating issue fixed then the high end rpm issue got worse. At the end of the season it would run great up to 2000 to 2700 RPM just about to get on plane and just stay there steady as can be. It would run like that all day but never give us anymore. I did find intermittant spark on 1 cylinder and that switch box was replaced with no change to the way the engine ran.

Spring 2021 changed out the primer bulb and fuel line got it running on the hose but will not idle and needs some throttle to get it to start. Dies immediately when the rpms drop below 1000 often with a cough or backfire. Testing the stator I was getting inconsistent results so I went ahead and replaced it with a CDI unit. No change so I set the idle timing.

I don't even know if my high end problem is still an issue because I can't get it to idle either on the hose or in the water.

Should I be looking at this as an ignition problem or a fuel problem? How should I proceed I don't know where to go with it.

Appreciate any advice