I had a problem with not having enough natural gas volume/pressure whatever to my brew stand. I needed 25' of hose to get from my gas hookup to the end of my garage. At first I tried the Charbroil brand, approved for natural gas hook up hose that you get from lowes, the real high dollar crap. I had to buy three sections of it. When I hooked it up, there was way too much pressure drop, so I bought 25' of 3/4" ID PVC flexible hose, and that big diameter ID hose took care of all my ills. You may want to try going bigger in size if you haven't already.
From the research I did, PVC is impervious to natural gas, unlike EPDM rubber, which is rated to have a severe reaction with natural gas. I know some people that do use rubber and have not had a problem though.