I've noticed my 2014 Silverado start to shake a bit more at idle recently. A slight jump in RPMs while sitting in drive at stop lights, no loss of power or anything like that. More recently it started throwing the P0302 code and every now and then the stability/traction light flashes on then off and my truck will shift down hard. I was at 115k with stock plugs so I changed all the plugs and wires, and the number 2 coil, along with the number 2 cylinders injector. All back together now it runs almost the same and the P0302 code will still appear, then clear, then back again. Could this be a faulty reading or is there something else I could be missing?