Yesterday i had to replace my bettary... and today when i was driving my '99 Montero sport to work... i stopped at a red light and it died. i had to put it into park and re-start, quickly giving it gas and heading off. This continued to happen every time my vehicle was stopped. It starts fine, so it shouldn't be my battery, but the problem only started after i got the new battery put in... HELP! please! I"m at a loss!

I dont know the Mitsubishi vehicles all that well...but if it started happening after the battery was replaced,it sounds like the idle has to be relearned.
Due to the loss of battery voltage,this may have happened.
Some vehicles require being driven for x amount of miles/speeds/drive cycles to allow the computer to relearn the idle.
Some may have to be relearned using a Scan Tool...this will require you to take it to Mitsubishi or a qualified repair shop.

Maybe one of the others knows the procedure for sure...

Jim

Jim is correct. It needs to relearn. Usuallly driving for a day or two will do the trick. The problem is a dirty throttle body. As the throttle body gets dirt the comp is continually compensating the idle up. When you replace the battery it goes back to square one which is way to low to idle.
You can get a can of throttle body cleaner (not carb clean) & clean it yourself, spray a rag & gently wipe around the throttle plate will hold the throttle open to get the heavy stuff & then run it & spray some down the throat while holding the throttle open just enough to keep it running while spraying