STIHL trimmer dies when letting go of the trigger

[Merkava_4]

FS 91 R 4-Mix.

Run perfectly fine and runs strong. Let go of the trigger and it dies. Starts right back up on the first pull and idles fine.

Put the trimmer back to work and it dies when letting go of the trigger. Rinse and repeat. I'm at a total loss as to why.

 

[EFSM]

Sounds like it could be too rich and floods out during deceleration. Has anyone ever adjusted the carburetor?

 

[hacskaroly]

I wonder if the low jet has a partial clog? Might be worth cleaning out the carb. Worth checking the spark arrestor too to see if it needs cleaning. Reminds me that I need to service the carb on my FS 91.