Here's the problem: I have an Echo leaf blower model PB-4600, many
years old, which starts easily & runs fine for the first two minutes
until it warms up. Then, if you keep on the throttle, the revs
suddenly drop and it stalls. If you release the throttle as soon as
the revs drop, it settles into a nice idle. If you then increase the
throttle back to operating speed, it will rev for a few seconds, then
the revs drop again, etc. Pretty frustrating trying to blow leaves
this way.

I've adjusted the carb according to the manual, didn't help. I suspect
some other carb issue but the puzzling thing is why the problem only
happens when it's hot. My next step is to take apart the carb and soak
the parts in gumout but, before I did, I wanted to check in to see
whether there was a known solution to this problem or if anyone has
suggestions on what else to check. TIA.