Here is one for you MECHANICS out there. A few years ago I did a max rpm Xy take off in my J3, when I pulled the power back it flat quit?? Nothing I did would keep it running below 1200 RPM. After several tries I dead sticked it in and towed it back to the hanger. Taking the cowl off and adjusting the idle screw did nothing. Both mags were good. Fuel flow was good??? Going to go flying for a couple of days I'll post the answer in a couple of days.