Hello, have a 78 Merc 800 with throttle problems, starts just fine, idles just fine, high idle; just fine. The problem I'm having is when applying fully throttle in gear, it runs as expected for 20 sec and then bogs down, almost to an idle RPM. Never stalls. If I leave it in idle and slowly bring the throttle back up does the same thing. Runs at full RPM, 20 seconds back to bogging down and idle. It's not over heating, at first I thought the fuel line was kinking; not the case. Thought the tank wasn't venting correctly so I pulled the cap; same thing. It's very strange, any insight would be greatly appreciated.
Thank you!
Thank you!