merc 150 bogging down

[phatdaddy]

i've got a 94 150 merc/mariner 2.0 carbed. it's got 1600 hours on it, still using the oil injection system. every now & then, when coming up on plane, it will hesitate and bog down. i usually can bring it back to idle for a minute or two, then hit it again and it will take off. i am going to change plugs & fuel filter for yearly maintenance. i have never had the carbs off of this engine.

the problem used to be every now & then, but lately it seemd to be getting more frequent, any ideas what to look at next?

thanks