My wife has a 2000 pontiac bonneville and we will be driving and it just dies. We’ve had some problems getting the car started. When we get it started it stays running for awhile, until the next time it happens again. We do know that the #3 spark plug is bad and it definitely needs a tune up. Is there anything else wrong with the car?
Start with the good tuneup and post back.
If this is a distributor based system, the problem may be as simple as a bad ignition wire from the coil to the distributor.