Billy,
Congrats on the new to you Rv. 1st , don't get discouraged while you work your way the the problems of new to you Rv . Sometimes it's an easy fix, sometimes not. We've all been there .
On the vibration . Check the age of the tires. Your Rv could've been sitting a lot and someone else mentioned flat spot. To check the age, it's usually found on the tire sidewall near the DOT imprint in an oval encasement, something like this (0610) the first 2 numbers are the week and the last 2 numbers are the year the tire was built. If you knew this already, sorry for the rehash., but you might have an old bad tire(s) causing vibration, happened to me. Sometimes the tire is mounted with the imprint towards the undercarriage.
Just a thought on the overheating. Did you replace the radiator cap with a new one when you flushed. I had a bad radiator cap caused my temp to rise.
When this happened to me on the ac prob, it occurred just before my alternator froze up, my compressor was working fine. Just a thought.
Check with Home Depot or lowes for material to insulate the engine
You've got a older puller, your close to the engine , more noise.
Not trying to insult you here but you have an entry level Rv , in the interest of weight management they use lightweight materials to build your Rv. More susceptible to road noises.not a thing wrong with , just the way it is.
More knowledgeable people here than me, but maybe some of this will help.
