98 Regal 3800 idles fine stopped in traffic. Led up on the brake on the creek port, the engine starts to stumble a bit. Apply the brakes to stop rolling until it clears up. Speed sensor?
No, it wouldn’t be the speed sensor. That’s just the old age and any minor thing can do that. On that particular vehicle, I’d advise doing my video "how to clean fuel injectors on your car" and if you’re not mechanically inclined, have a mechanic come and do a fuel pressure cleaning of the fuel injection system. A lot of times, dirty fuel injectors do that. And of course, since it is old, if it needs a tune up then have that done. If the spark plug wires are old, change them. If the spark plugs themselves are old, change them as well.
It could just need a tune-up. Since you are just idling and then stopping and going, any minor flaw is going to show up, and you’re not going to notice it while you’re driving.