I don't know much about the stage 2 drift motor (I just have the stock motors). Have you checked the drive-train to make sure everything is rolling smoothly?
As a general rule of thumb, I always use rechargeables (preferably nimh at worst, li-poly at best) in my RC stuff. You might consider investing in some nimh AAAs. Try
www.batteryspace.com - $19.00 for 24 700mAh AAAs (charger extra).
Yup, the right rear hangs low on both of mine. Yours isn't bad; it seems to be a design flaw of sorts. However, I've found that the car sits evenly when resting on a surface.
If you want more power, try going with a 5-cell or 6-cell AAA mod. This will give you much more punch right off the bat (but also shorter motor life). Mine scream with the 7.2v li-ion packs I hacked together.
I've found that xmods are pretty hearty; it takes a lot to damage or break them. They're pretty well designed and put together.
pbmax