I have a 1998 150v6. I have not gotten to take out in awhile. The last time I did I was not able to keep it running at the dock without using the throttle. I then was not able to get up on plane. Took it back home and pulled the plugs, all seemed ok but I changed them just to be safe. Took it back out the next day I could and still had the same issue. The last good running day I had run it at idle and did alot of trolling, then before returning to the dock I made a few passes around the main body of the lake. I didn't get to use it for quite few months due to a very unseasonable north Texas winter. Then this all started.I know that it has new plugs and fresh gas is getting air but am not sure what may have cause all this at once, any idea's would help.
i would bet that the carbs need to be cleaned, sounds like the low speed or idle circuits are dirty, i have had many yamaha's and the carbs need their attention,not hard, not easy, but easily do able good luck