My 1999 Grand Prix is well-maintained.
After an oil change it started to consume gas and oil as usual for a week, then started to shake when idling, and slow and gaging when accelerating and feel like no power.
I changed spark plugs but it's still not working. The tester said misfire on #6, changed all spark plugs but still not working. Please help, thanks.
It sounds like you may have a coil pack which has gone bad on the #6 cylinder. The easy way to check this is to exchange the coil pack with one of the other two. If the problem follows the coil, then the coil is bad. If the problem stays at the same cylinder, consider your spark plug wire may be at fault. If the coil is what's bad, you'll need a replacement.
