My coleman evcon c0at066BDB in my mini home is very noisy and disruptive. How can I fix this nuisance? Also, the furnace did not have any filters when we moved in and I cannot seem to find a filter to fit a 19 inch door... is their a special filter needed?

If you had no filters in the system at all, That's your problem the blower wheel will have a lot of dust in it throwing it out of balance. Check to see if you have a filter behind the return air grill. You can buy cut to fit filters just about from any place you can buy filters.