Idle Issues - 1989 Merc 9.9 OB

[Chris in Indiana]

I've got a 1986 Merc 9.9, 0B398065 Ser No. It's fairly new to me but when I bought it last year I had a mechanic clean and adjust the carb, but no new parts were necessary except I did add new plugs. It ran great at the time. This season it's hard to start and won't run for long at idle. It seems to take forever to warm up and get going, but once I get it in gear it runs great under power all day. If I go back to idle it will run for a minute or two and die, even with the adjustment turned all the way to fast idle. Any suggestions on where to start? Adjustment issue or fuel pump? Incidentally the idle speed adjustment seems to have little effect, where as last year I could absolutly hear the idle speed change when adjusting it.

Thanks in advance!