Sounds like you seriously need to richen that thing up... if it isn't too late.

Be drastic with it, to begin with. Everything you post indicates lean/hot.
("only putters" "runs on prime, then must prime again to restart", etc...)

If richening the needle up a turn to two turns, then working inwards from there,
doesn't help... you're gonna have to run more shims, or drop some nitro or something.

Trying it richer certainly is a quick and cheap test.
I am assuming that your tank/lines/needle have been thoroughly inspected.