Mixed up the Mechanic-in-a-Bottle per the instructions (1oz + 1 gallon of gasoline). Put it in the leafblower, ran it for 15 min. No effect. Let it sit for a few hours. Still nothing. Poured 1/2 oz directly into the leaf blower's gas tank, ran it on idle for a minute, success! I can once again open the throttle without issues. It still feels like it's slightly underpowered, but it's at least 90% of what it should be. So that's great news. Best would be to clean/ replace the carburator, but I'm happy if this thing lasts until I sell my house
Thanks everyone for the suggestions. Easy fix for $4, hard to beat that.