92 Evinrude 120 E120TLEND backfires when idleing

I just replaced the plugs which were a little help but didnt fix the problem. It backfires about every 1 second when idleing. Also when i spray carb cleaner into one of the carbs the engine revs, when i spray into the other 3 carbs the engine bogs. Is that a spark issue or a carb issue?

The carburetor that revs higher when you spray cleaner into it is the offending carburetor, running lean due to a air leak (seal to intake manifold?), or possibly a idle air bleed jet whose inside diameter is slightly too large. The size is imprinted right upon the jet... try the next size smaller.

If the engine has sat for quite some time, it is also a possibility that a small fuel passageway from the float chamber to the top slow speed passageway is somewhat fouled, in which case the carburetor will require cleaning and rebuilding as needed.