Pro 110, runs 10 min., blows white smoke ,shuts...

Question

I have a Reddy Heater Pro 110, several years old, has been a good heater, usually run kerosene, recently running diesel #2, have run several tanks through, no problems, recently acting up, will run for 10-15 min., then blows puffs of white smoke sparatically until shutting itself down or me unplugging it, i have no manual, have turned screws, lost track of correct position, where are screws suppose to be set, do i have other problems, ive cleaned spark plug, replaced fuel filter, cleaned air filter, ANY HELP? THANK YOU.