Might be the IAC motor. Should be able to find lots of posts on that if you do a search. It's a little motor that goes into the throttle body and allows a controlled amount of air in while you're at idle. It can get gunked up or just wear out to the point that you'll eventually stall at every stoplight. You can pull it out and wipe it with a dry rag but don't spray anything on it. Could also just be a dirty throttle body. Pull off the air tube and have a look. Even a small amount of gunk around the edges of the throttle plate can cause idle problems.

98 Montero, 184k.