Thank you one and all for the help and suggestions! There was not a dead rat in the air intake. Hunter did not design a system that did not let in an adequate air supply. 1. The low RPM was caused by a clogged opr carboned up mixing elbow. I forgot who to thank for thie tip and the recommendation to check the archives, but thanks again. 2. The deisel burping was caused by too much oil in the crankcase. So much for professional oil changes. I finally noticed that the oil was way too high on the dip stick. Changed the oil and just put in the proper amount. The engine ran at 3400 rpm under load for an hour and no burping. All is well that ends well and many thanks to the Hunter Owner's community for all the help.