I was driving home recently when i went and pushed the brakes for a stop sign and my 4runner pulled really bad to the left. I was wondering if the brake on the opposite side is going bad or if it was somthing else. Any other ideas would be helpful. Thx

 

warped rotors?

 

Nah that would give a vibration upon stopping.

Look at the possibilities of a stuck piston (which would require a new piston seal or if you don't know how to do it, buy a remanufactored caliper), misadjusted shoe clearance on the left side (too much space), air in system lines (causes the side with air to absorb some of the compressing of brake fluid), and misalignment.