89 Buick Century I use on a mail route.    Car runs fine for a few hours and then suddenly begins to stall after a make a stop and try to pull off again. Runs rough at that time also. Will always crank right back up but knock off when I put it back in gear. If you leave the car an hour or so until it cools down some, it will then run fine again. This is an intermittent problem but becoming more common and frustrating when you have a car full of mail. Thanks.    Tony