Problem solved and thanks for all your help... I had the loco on two throttles!

I have three Bachmann DCC locomotives running on Digitrax DCC. One runs perfectly. One other actually tries to run even though the power is off. When it does run, it hesitates or stops sporadically. The other has sound and also hesitates, stops completely, and occasionally will not run when power is applied even though the sound is on. I have cleaned the wheels and track. Any help?