My Johnson 7.5hp will tool along just fine for hours at trolling speed. If I open up the throttle it goes great fro a short time then bogs right down. If I back off the throttle quickly I can keep it running. I can nurse it along like this for a while an then It will allow full throttle for a short time again, although it does not seem to go at full speed. Yes tank is vented and fuel is fresh, plugs are new. Can anyone help?
