My 99 Marauder sat up for quite a while. I put it up with StaBilt in the system. When I took it out to ride I drained the fuel system. It would not idle and backfired. I took to the shop and for an terrible price they told me I needed to replace the Air Cut Off valves. I bought the valves, cleaned the carbs, installed the new valves. Still the same problem. No idle and backfiring. Changed plugs. Even removed and plugged off the PAIR valve. No joy. Still no idle and backfiring. Anybody got any ideas? It seems to be the back cylinder.