Read somewhere that Echo switched engine makers from Kioritz to Yamabilko some time back, just throwing it out there FWIW.
That is really strange. Maybe the screen arrestor or the secret carb needle (I know the 225 has one)?
I am suspecting that the carb on your trimmer needs adjusting, but of course it can't be adjusted. I am about to buy this adjustable replacement carb for my Echo PE-2201 and will post back with results when I get it. If it works for me, it's probably worth trying on your unit.
Mine is under warranty. They replaced the carb on the first unit twice. Not sure what they are going to do with the second unit. I am running one of the dealer's 266 units for now. I agree that is sounds like it needs a carb adjustment but no adjustment.
Read somewhere that Echo switched engine makers from Kioritz to Yamabilko some time back, just throwing it out there FWIW.