Newbie rider: 96 Katana 600 surges while running
I'm having an ongoing issue with my 96 Katana 600. For the most part it runs well, however, at pretty much any RPM the engine runs slightly lower RPM than it should (for example, idling below 1000) and surges a 1-200 RPM every couple seconds (somewhat randomly)
The carbs were cleaned before I bought it and I ran seafoam through it as well, which greatly improved on how it was running before (basically all the symptoms of needing the carbs cleaned again). But this issue remains.
Another oddity: at highway speeds, the surge seems to be more of a lag: the RPM drops instead of rising.
Things I've tried are running seafoam through it, tightening the chain (which made it run more smoothly, still didn't fix it) and replacing the air filter. I'm too scared to do anything else and too poor to have a mechanic look at it.
I don't want to start digging around without knowing what it is.
Thanks for any advice.