I know this is an old post but I have the answer. The Thor 45cc is a fantastic engine but the ignition module is a piece of crap.
I talked to global and they said that the module must have a 6V 3500 mAh Sub C pack to work properly.
I was having the exact problems you are having on my thor.
I replaced it with a brison ignititon and it now runs like a top at idle and top end...
I use a 2500 mAh 6v nimh but this module works great with a 4 cell 600 mAh pack.