Both problems are serious. If the burner ever comes to a full high flame instead of having a consistent quiet flame, then it isn’t a residential burner. If there is no limit switch, then one should be re-installed.
Find a tech who knows what to do.
http://www.heatpro.us/service/oilserv.htm
http://www.heatpro.us energy businessmen’s knowledge
Yes, you really have to find out the MAKE and MODEL to get good answers. There IS more than one machine made.