2000 Pontiac Grand Prix Car ran rough now won't even start

Scan the computer for code/s

Also check the following:

Possible causes include a bad O2 sensor, excessive fuel pressure (bad fuel pressure regulator or plugged return line), leaky fuel injectors, dirty air filter or restricted air inlet, or a defective coolant sensor that prevents the engine management system from going into closed loop mode.

Scanned the car and found that cylinders 2 and 5 were missfiring. Replaced the coil (2 and 5 are on the same coil) and that did not work. Now they say it might be the ignition module. Ordered one today. Would the module cause a constant miss like that from just the two cylinders?

Could be compression or injector problem on those cylinders. Engine misfires can be caused by worn or fouled spark plugs, a weak spark (weak coil, bad spark plug wire), loss of compression, vacuum leaks, anything that causes an unusually lean fuel mixture (lean misfire), an EGR valve that is stuck open, dirty fuel injectors, low fuel pressure, or even bad fuel.