Hello and Welcome to Just Answer,
It sounds like you are on the right track, I would look at the fuel filter first. On your year model chevy typically used a mechanical pump on the front right lower engine, that was driven by the camshaft. The fuel filter was typically located at the carburetor inlet connection. Being a motor home it is possible that the location could be different.
So normally there would not be a suction filter between the tank and the mechanical fuel pump?
Thanks and let me know if I can help you more on this