I need a little help. Two weeks ago my wifes 1999 trailboss started idleing very fast while riding so we shut it off .When we restarted it it backfired very loud one time and continued to idle to fast.we went back to the truck and changed plugs and it was fine for awhile then started again.they want to go this weekend so i would like to fix it but dont know where to start any ideas.thanks