[jhautz]

You said that one of the connectors to the motor came off at some point. Did you solder it back on or what exatcly happened? Sounds to me like its severe coggin, like what you would get if the motor only had 2 of the 3 phases connected. I would double check all of your connections on both the motor and the battery sides. Give all of the solder joints a good hard tug. If they are correct you will not be able to break them. Also check that the plug itself didn't get damaged when it came off the first time. Or it might have been damaged and thats why it came off in the first place.

Bottom line make sure all of your plugs are good and your solder joints are solid.

This problem really sound to me like its a connection loose somewhere in the system. Probably on the motor side.

Just my opinion.