Gauges not working should not make the coach " ride like a school bus. "
Do you have any information on your Freightliner chassis build date .
Your 2008 coach could be on a 2007 chassis and Freightliner changed gauge packages during those years.
Build date decal should look like the photo below.
99DSDP 3884, Freightliner, XC, CAT 3126B, 300 HP /ALLISON 3060
2000 Caravan toad, Remco & Blue Ox.