2017 FC350 surging, won't hold steady rpm

Bought used with only 5 hours and in mint condition. I put 2 hours on it so far. The bike starts good and I can wack the throttle open and it doesn't bog, runs good when winding it out. Issue is it won't hold a steady rpm mostly at low throttle like just going around the yard in 1st or 2nd gear, it wants to accelerate then decelerate like hunting I guess you could call it. I'm thinking a lean condition would cause this. I changed the small inline fuel filter, didn't help. I had drained the old gas that was in it and filled up with 75% 89 ethanol free mixed with 25% 110 race gas when I brought it home from the dealer. I'm thinking the fuel filter in the tank or partially clogged injector since it sat a lot before I purchased it and maybe I have varnish issues. One other detail is it runs better on map 2 than map 1. By better I mean the surging issue is less on map 2 for some reason. What should I check next?