I had an issue with my 62 last year. About the same thing I would take off (full throttle) as soon a s I back Out to start manuevers it would die. Myself and others couldnt figure it out, mixes throttle position, air leak<---(might look for that, the black spacer will crack if its to tight) I even rebuilt the carb 3 times before I chucked it out in the yard. So on to RCU for a new CARB and BINGO no more problems. $35.00 fix for me. well worth it. No more frustration. I would consider seriously looking at the ventury and all carb seats and the plastic throat it sits on. I found a crack in mine just last week. Good luck.