Gearing problems.

Hello everyone, I have a LEGO steam locomotive MOC, but I have some questions regarding gearing. I figured this is a good place to ask for help on that subject. I currently have my locomotive geared for torque (12-20), but the locomotive sometimes slows down, makes screatching and/or grinding noises. So I was wondering if using a differential would be better, though I will lose torque, and gain speed.. This is my current setup. (Some support bricks removed for the picture) Would this be...