Johnson Bogging at WOT

[NC Angler]

My recently rebuilt 1968 johnson 9.5 just started fluctuating/bogging down at WOT. I have been using it all summer with no major issues except it bouncing around while I'm towing the boat which seemed to have caused the entire unit to shift rearward in the frame making the choke linkage and high speed knob not stick out of the face plate far enough to operate.

When the motor bogs at top speed the whole unit moves back and forth within the motor frame. The speed slows way down for a second like the motor is taking a big gasp of air the speeds back up. Just below WOT I don't have this issue. It seems like maybe air or water in the line but I'm no expert by any means which is why I'm on here lol any help is appreciated!

 

[racso]

I had kind of the same problem tried a lot of things until, i added fuel treatment to the gas ,, i use regular gas 87 octane so i think the fuel is duty and collects humidity .. maybe you want to try that

 

[NC Angler]

Ok racso ill try some sea foam. Last week I used some "100% ethanol free gas" thinking that might be better than regular 87 that mite corrode my fuel lines over time. I wonder if that had anything to do with it