Try looking at
this document, which explains how to calculate forces and how to pick the right motors and gear ratios for your mechanism.
In short, if you're pulling 10 amps, you're running at about 20% efficiency (based on the motor curves), which means 10 A * 12 V * 80% = 96 Watts getting turned into heat with nowhere to go. Generally, you should run motors close to their maximum efficiency, which for the Denso window motor would be a torque of about 2 N-m and a current of 5A.