1997 Pontiac Grand Prix Backfired now wont start

If the engine's condition is in tip top shape-do below to determine if its fuel or spark problem that's if its cranking over and refuses to start

Get a carb cleaner and spray into the carb or the throttle body on an EFI. Did it start and die? If not disconnect a sparkplug wire or 2 and ground it to the engine -have helper crank engine over-do you have a snapping blue spark? If so-you have a fuel problem, check the fuel pressure to rule out the fuel pump/pressure regulator and listen to the injector/s are they pulsing or hook up a noid light. No snapping blue spark continue to troubleshoot the ignition system-power input to the coil/coil, distributor pick-up coil, ignition control module, cam and crank sensors-

If both fuel and spark is present-check the valve and ignition timing, this will lead you to problems with compression and valves opening and closing at the wrong time

Also be careful on this engine with the plastic intake plenom usually break when they backfire. Look for holes in it and be careful when trying to start.