i developed a similar problem on a PA50.. the bike restarts with some peddling and a wide open throttle. This problem started right after i cleaned the carb last night.. very weird.
I get the strong feeling that my needle is sticking closed...
The float bowl starts out full, the float drops but the needle is stuck, and the bowl empties to the point where the float level is low enough that the engine dies (at idle). Then as i peddle and twist the throttle and generally shake the bike the needle drops and the bowl fills again.
Here's what i suspect is happening..
The needle attachment to the float is loose and has some free play, so the float has to drop so low that it actually pulls the needle open. But by this point the idle circuit is too lean to idle the motor.
Right now im doing some mechanical work but later i'm gonna pull the carb and see.