Could be a solenoid issue…all the Stihl M-tronic saws require a solenoid, fuel filter, then software reset from time to time to keep them happy. The fine screens in the solenoid and fuel filter can get plugged up with fuel contaminants etc pretty easy it seems. We switch them out often at work and it makes a huge difference… new solenoid, new fuel filter, and then do a reset for your M-tronic software version. It’ll tell you what software version you have on the label attached to your hand guard... or sometimes chain brake handle. There’s a few different resets depending on the age of the saw. We swapped all our white solenoids and fuel filters out for orange ones and it’s been nite and day. It’s pretty basic and there’s some great content online to help out. Best of luck!