rzr will crank and run but after a little while it starts to backfire threw the snorkle and the exhaust. It will barely run 10 mph. Its like its running on 1 cylinder. It has a total loss in power. It returns to idle when you stop but some times it will go dead. It also spits and spudders. Any ideas? It seems to be getting sparks on both cylinders. When you mash the gas to floor its sounds like luuuuuhhhhh poof poof... Picks up a littls.. Then sams sound.