I have a 2000 Chevrolet 2500 with a 350 vortec in it. I was driving down the road the other day and i felt a little slugishness in it then it started misfiring real bad vibrating the whole truck. the more i accelerated its starts to backfire repeatedly I have changed the plugs,& wires and removed the distributor cap and it looks fine with no cracks or burns. the ignition coil is my next thought. It has had an 02 sensor out for a while on the right side. Any help is appreciated.