ORIGINAL: hobby_man
It took me 13 tries to figure out why the motor would not run in the air.
darn thing ran fine on the ground after I got the new carb!
I'm confused again. You said you replaced the old carb with a new one and that it ran good on the ground, but not in the air. Also, the old carb had junk in the filter which explained why the engine ran so bad for 13 flights.
Now that you know why it won't run in the air with the new carb, what was the problem? Cowl air pressure changes, cooling, or something else?