GMC Troubleshooting Questions? Ask a Mechanic for Answers
That's a bummer. Sorry you have waited so long for a reply. Are you able to get the codes? I would bet it's just another bad ignition coil. If you can't get the code, you can do a power balance test by unplugging the fuel injectors one at a time and which ever cylinder has no drop in rpm when the injector wire is pulled is the misfiring cylinder. It would be best though to get the code. Let me know what your code reads.
That sounds normal. When you get the code let me know. Thanks