There should be a screw related to the linkage vs carb if you look close. I feel something is miss aligned (if you look close) if this has not always been a problem.

Thanks for the reply. I guess after reading I wasn't entirely clear. I know the screw you are talking about. I can adjust that lower, but the engine stops running when I get too low, before I can get it idling at a low RPM. There's another screw that looks like some sort of needle adjustment but it's square on the end. It also doesn't do anything until it's completely removed.

Started last fall but put it off until now.
Thanks

How old is the trimmer? My Stihl needs a carb rebuild every 3 years or so. The new gas kills the flexible parts in the carbs.

A carb rebuild kit is only a few bucks at the Stihl dealer and it is a fairly simple process with hand tools and Utube vids. If your trimmer is more than 3 years old, it might be just as effective to pull the carb and rebuild it completely.

Get a new filter/ clunker for the tank while you're at it so it can draw plenty of clean fuel.

Have you used Stabil or any additives for the corn gas per tank used (if you use corn gas)? I have treated 2 gals per purchase since the start of corn gas and have not seen one related problem yet.

A good inspection for deteriorations (fuel lines, diaphragms) and cleaning (screens, etc) would be a good idea with these symptoms (as mentioned).

Are RPM issues usually a sucking air matter or what?

Good Luck!