Hi, Welcome!
Can't help much with the A/C issue without more info or pictures. Is it actually ducted through the coach ceiling? Make/model of A/C?
Can you furnish info about the Thor Coach? I can't make sense of "21ft 5K."
The Chevy Lovers are gonna have a field day with "white knuckles!" As a rule, the handling issues with E-Series aren't too bad with the smaller (shorter) RV's. How many miles on this?
What Tire Pressure did you run? FRONT tire pressure is critical. If the tire sidewalls say 80 and you run that, it's gonna handle like a squirrel on espresso.
Single or dual rear wheels?
Load it as you would for a trip, and drive, crew and all, to a truck stop and weigh it. Post back.
