your automobile has electrical issues, these are common of the grand prix model, these issues can be overcome by taking your automobile to your local shop and get a qualified technician to diagnose your automobiles malfunctioning electrics
My car started missing so I change the plug wires and the plugs thinking that's what it was it still missed I saw on YouTube how to check the spark on the coils found one coil that wasn't sparking sorry placed all three still did the same thing so then I checked and had my ignition modular check said it was bad got a new one same thing still missed when I got another modular and a different coils now missing I don't understand
Have the error codes been checked? If not get it done at your local shop or parts store and see where that leads you. Still many things in the ignition system that could be the cause ans several things that exhibit the same symptoms in other systems like inbound air flow and even exhaust system (catalytic converter or O2 sensor). Having a code check done would be a good place to start.
Check for a bad fuel injector on the missing cylinder. If that's ok, you should have spark and fuel on the misfiring cylinder. If so, compression test the misfiring cylinder. You may have a burnt valve. If your compression reading is low, less than around 100 PSI, the cylinder won't fire. HTH. -Jim
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