[fdheld34]

I have a 1993 Merc 135 hp..same block as 200 etc. I purchased engine about a year ago fresh water only and it ran great when I first got it as well..same symptoms as yours. I replaced fuel tank, lines filters etc but to no avail. Took it to mechanic and he had to rebuild all three carbs....gunk in carbs...said engine was sitting a while and then got clogged up....now it runs/idles etc like a brand new engine. Find reputable mechanic and take it from there...I am not mechanically inclined so I cant offer any more advice. Only thing I can say is don't mess with engine yourself if you dont know what you are doing..will screw it up worse..especially linkage etc.
Fred