The furnace is less then 2 years old and has done this since day one. On days where the temp is mabe 45F or 55F outside and the demand is very seldom, the furnace will come on as normal. The problem is the left hand burner has a flame that does not go into the tube all the way. Most of it does but it waivers and finally blows out only to reignite and make a slight boom noise. Sometimes the furnace will shut itself down only to come back on several minutes later. On cold days where the temp is 30F or less there is no problem. The left hand burner is the first one on the supply run. All 5 burners are aligned and seem to do just fine on colder days. Could this be a pressure problem?