Heat and noise from the engine compartment are more a function of the body builder than the chassis builder. All engines make noise and dissipate heat. However the way it's dealt with is totally different between motorhome manufcturers. We're on our second Winnebago on the F53 chassis and neither has had a heat or noise problem. Winnebago took the time to design an engine cover that allows good air flow past the engine and does a good job of keeping the noise and heat out of the passenger compartment.
There have been several threads on this and other forums about people purchasing and installing after market insulation kits for the engine cover. Most have been very pleased with the results.
Poor performance may be due to a partially plugged fuel filter as mentioned earlier. Last year we had trouble with our 2001 Adventurer pulling our Jeep through the mountains. We new something had changed since we had taken the same route several times and never had any trouble. When we stopped in St. George Utah I looked through my maintenance records and noticed the fuel filter replacement was long overdue. I purchased a filter and installed it the next day. The old filter weighed at least 5 lbs. I was surprised the engine even ran with the amount of junk it collected. There was a noticable difference in performance with a new filter. Hills and mountain roads we struggled on earlier in the trip were no longer a problem.