Kristin,
Yes, microstepping will reduce torque somewhat. But, if you're having problems with the motors stalling, your real problem is that either:
a) You're pushing the machine too hard or,
b) Your motors are too small or,
c) Your controllers are not very good, or are limiting current (Geckos are highly recommended) or,
d) You're not running high enough power supply voltage or,
e) Any combination of the above
What kind of machine is this? What size motors? What, if any reduction (including leadscrew pitch)? What stepper controllers are you using? What is your power supply voltage, storage, curring capability?
Regards,
Ray L.