I really appreciate all the good advice. Well we ended up having to change out the furnace after all. Local RV guy had one in the next day $$$, as the manufacturer wanted us to send it to them because they couldn’t figure out what was causing the problem.
Still working on the toilet. Tried the vinegar and cleaned the seal. Will wait until spring as it’s 10 degrees and can’t turn the water off without removing all the insulation I’ve built around it. It’s a second bathroom so we can do without.
Some other things that might help RV’ers. Our cable connection had a very high db test that was affecting our satellite internet. After finding the coax splitter behind a wall in the storage compartment we figured out it was defective. Again the manufacturer told us to send it to them before they would replace it (I guess they don’t believe us) I rerouted a coax cable through the slid out to the modem.
The leak under our kitchen sink was fixed by me cutting off the fittings and replacing them as they were cross threaded.
We’re still trying to figure out how to keep the oven on as we think the fan keeps blowing it out. Thank goodness for the convection microwave.
Thanks again for all the advice and we hope this helps others.