2002 Yamaha F30 Misfire under load

[ijmunro69]

Tearing my hair out. Outboard has been to a Yamaha registered repair shop twice now and I have spent a day on it and still not found the issue.
Basically can hear it stumbling and misfiring when under load and when on the water means you can only run at half speed or less to get home.
1. Dealer changes plugs and cleaned carbs. Also ran it off a separate fuel tank so ruled out bad fuel or primer bulb/hose blockage.
2. I also took fuel pump apart and it looked fine but wasn't sure whT. Bad one looked like. Hugely simple bit of kit.
3. I also stripped carbs right down and cleaned each one

I can't tell but oil may be a tiny bit thin. Doesn't look like it's overfull though as it would be with fuel pump leak.

Idle is ok without being superb but under load is when its as issue.

Any other things I haven't though of?

 

[Seastoke]

Coil. ,!!!

 

[ijmunro69]

I put the meter on them and they all tested ok but I guess they could be showing the fault only under load??
Not used to three small coil packs for the 3 plugs!
Also unplugged them one at a time and they all had an effect on the rpm.
Open to all and any testing suggestions though rather than replacing them all incase!

 

[Milgrip]

As the fuel side has been sorted, and with regard to the age of the engine and years of wear & tear, have you tried running with the cowling off as possible excessive engine breather fumes can affect performance, but coils or plug leads breaking down under load are more likely contenders.