I have an Onan Emerald 3 gen set on my 1981 Holiday Rambler. I bought it a couple months ago. I went to start onan and ended up replacing the circuit board fuel pump, and air filter. I changed the oil, filter, and spark plugs. I ran a new fuel line to tank and put a new muffler on it. I took carb off, and cleaned it. When I start it, it sounds really good, runs for about 25 minutes, and sputters for about 10 seconds and dies, with little to no load. The engine was around 280 deg.F. I noticed mice nest around engine, I cleaned alot of nests out, blew it out with air. Started again, runs for about 25 minutes, sputters and dies, still hot. Also, on dipstick, do I check oil level by screwing it in or just resting on the threads?