We've had our 1997 Endeavor LE for over 9 years and it has given us good service. Very few problems and those we did have, HR took care of, some even after our warranty was long expired. However, we have the Freightliner chassis and Cat engine and I believe these items are a big factor in the reliability of our motor home. Newer Endeavors are built on the Roadmaster chassis and use Cummins engines. I'm not sure what was used in the 1999 models.
As with any manufacturer and models, you can get lemons, but I hear fewer problems about Holiday Rambler products than about most other brands. Do your due diligence as you would on any used RV and hopefully, you'll avoid the bad ones that are out there.