I have a 2005 Husqvarna YTH2448. It has a Briggs & Stratton 24 HP ELS V-twin engine. The engine runs but it runs rough (lopes, rpms going up and down and almost sounds like it is backfiring especially at high idle, low idle it doesnt run as bad). I've taken the carb off and cleaned it but did not rebuild it yet. If I pull the plug off of either cylinder it runs like a new mower, as soon as I plug one of the plug wires back onto the plug it starts running rough and missing, both plugs have great spark (grounded the plug and wire to the block), I've put new plugs on it, drained the fuel tank and used higher octane fuel, new fuel filter, new air filter, changed the oil, cleaned all electrical connectors, re-gapped the Magnetos, and still have the same problem. It's starting to get expensive replacing parts. Can anyone give me some direction as to what I may try next? Thank you in advance for your help..