When I pulled the little Sears in my signature out of the barn this spring I noticed that the engine was revving itself up and down. Not enough to cause concern, but enough to notice it. Since then, the surging is getting more and more dramatic to the point that the machine is getting difficult to use. Here is the strange part though: it isn't a constant problem. I can go an acre without incident, spend several minutes fighting to keep it running, and then set off for another trouble-free acre of mowing. Load and engine temperature do not seem to have any effect on this problem one way or the other. In fact the only constant factor I can identify is that going over bumps or turning at high speed sometimes sets it off. I have sprayed the carb with cleaner and I've poured a quarter can of Seafoam into the gas tank, neither of these seem to have been effective. I'm convinced it is a carb issue because nothing else makes any sense... I just don't know what the issue is! Every other carburetor problem I've ever had was so much more consistent.
I'd like a few opinions/suggestions/ideas before I order a carb kit. I don't like troubleshooting blindly.