Chevrolet Repair: 1998 camaro V-6 P0300 code, coil pack, plug wires

Question
I have a 1998 Camaro V-6, 5-speed manual. The car isn't running on all cylinders. Ran the SES codes, came up P0300. Thought it was the coil pack. Unplugged spark plug wires from each one to see what one was not functioning correctly, It was the back one, cylinders 1 and 4. Replaced it, no change. cleared the codes, went to drive it to get a new code, hit a bump, car ran fine for a while. Later that day went driving again, problem came back. So the problem is in the 1 or 4 cylinder. Not sure if it is one or both. Looking for any help I can get.

Answer
Now you said it was the back one...1 and 4?  Number 1 cylinder is the front one drivers side and the 4 cylinder is passenger middle.  If you have a coil not firing you may have bad wiring issue at the coil, or from the PCM. The only way to check that is to OHM out the wires from the PCM connector to the coil pack.  You will need a connector end view to figure out which terminals to test on the PCM, which I can not send you via allexperts...won't allow images to go through.  If you would like, I can email you this diagram if you would like to go further  with your car,  Also when you do test the circuitry test it when the issue happens, then shut the car off.  Because if it is the wiring when you test it if it runs fine you will never find it.
Jimmy