I have a masterbuilt smokehouse. It's the vertical propane one. First time I used it the smoke went flawlessly. Second Time I had a thick black soot on all the meat. I got some great suggestions about cleaning the burner and checking for spider webs. This weekend I am smoking some pork butts for a church event and I need some advice on anything else I can do to prevent this from happening again. I cleaned the burner good and the flames are blue with orange tips. Also any suggestions on how many butts I should do at one time on this smoker? Thanks in advance