"trophy".....That coach has two issues, one that is minor and comes up on occasion..... that is the idler pulley for the fan belt. I've seen many of those go bad, including the one on the 2004 8.1 that I had. Should be easy to find on the road and can actually be changed through the right front fender well.
The second issue are the spark plug wires. That engine configuration did/does not get enough air flow across the exhaust manifolds and the spark plug wires eventually break down and start miss firing under load. There is a brand called Taylor that many use as a replacement, but buy their best quality model.
If you get a chance, take something like dryer vent tubing, and route some air form the grill to both sides of the engine/exhaust manifolds.