I have a 1999 500 XC, i just put new gas in it, new plugs and stuff, and it wont start. I have no idea whats wrong. It started earlier like a month ago, then it had a big backfire, and it hasnt started since. it almost starts, you can get it almost going, then it dies. then i takes a while to get it to almost start again. I have checked everything i know, including the fuel on and off button. do you guys know what is wrong?? thanks!