Let me try to sum this up. A few months back I had my H in a parade, it was the first real use after a complete overhaul. At times it was acting like it was running on one cylinder, black smoke coming out of stack, not much power. Other times it was fine. I blamed that on the spark plug wires not making a good connection to the plugs. Installed new spark plug connectors and new spark plugs, now it is a tight fit. Sitting in the barn it started with the first spin of the flywheel and ran just fine in the barn for a few minutes. Month and a half later I tried to start it and all it will do is fire for a few revolutions then die. It will fire almost every time I spin the flywheel but it will not stay running. Might run for 10 to 15 seconds then die. It will only run with no throttle. If I give it any throttle at all it will not even fire. I noticed a hissing sound when I was spinning the flywheel. The hissing is coming from where there intake manifold and block come together. You can see in the picture there is a small gap. I squirted a little WD-40 on the gap and when the tractor fired for a few seconds it sucked the WD40 in. In order to remove the manifold the hood has to come off as well as the fan shaft. Does this leak in the manifold explain why the tractor will not stay running? The gap was always there because I remember having to put some gasket sealer on it at one time. There is an actual gasket between the two but apparently it is not thick enough to fill the gap. Maybe the long parade ride got things good and hot and the gasket sealer burned away? I hate to have to tear this down to get this manifold off, any other "easy" fixes for the leak? The fan blade shaft is about half an inch above the manifold so that is all I can lift the manifold up. Thanks to any suggestions.