40 hp 1993 low speed throtel problem.

[legalas]

Any body any ideas why my engine at lower speed slowly starts to either gain speed or slow down by itself after anywhere from 30 sec to a few minutes ? Cheers

[boats.net]

Low compression, air leaks in intake manifold or crankcase, plugged p***ages or jets in carbs or misfiring on one or more cylinders.