check engine light comes on after 3 hours of driving and only after refueling have replace plugs wires 1 coil filter and 3 gas caps
Sounds like you may have a problem with the purge solenoid in your EVAP system. https://www.youtube.com/watch?v=o_kxHJkzF-I
Do you get any other codes other than the multiple misfire? It still could be the purge solenoid. Try putting in a can of SeaFoam in the fuel see if that helps first.
It could be multiple things. you need an oscilloscope to see what your vehicle is doing. I came across an issue with a vehicle having random misfires and it was out of timing
Looking for a Used Sierra 2500 in your area?
CarGurus has 159 nationwide Sierra 2500 listings starting at $5,795.
Search GMC Sierra 2500 Questions
GMC Sierra 2500 Experts