Up until a few months ago my 2006 500 has been running great. My son was riding it in the yard one day and I noticed that when he'd let off the gas it would backfire a little bit but I didn't think anything of it. This last weekend I took it up north deer hunting, before leaving I stopped at the gas station and filled it up. The first time I had a problem with it I was driving down the road at full throttle and completely let off the gas, the engine reacted as though I had turned it off, it came to a complete stop and backfired that sounded like a gun shot. It started right back up again and again I went full throttle down the road, the same thing happened. I took out the spark plug and it looked fine, unfortunately I couldn't find a store that had a replacement plug. After I put the plug back in it seemed to behave a little better but it still acts like it wants to die and backfires a little bit. I found that if I feather back the throttle instead of just letting it go it doesn't act up quite so much but obviously something is wrong. Could this be a bad plug? I'm not sure if this is related but the battery is still the original and depending on how often I ride it needs to be recharged every once and a while. Any help would be appreciated, thanks.
