galaxyob1,
Newer Foxes don't need as much break-in as the older ones did, but they DO need some break-in. You can check whether it is broken in by running it at flying RPM. This is best done on a bench but can be done in the plane. Start it and lean it out but not to peak. If it runs a whole tank without slowing down it is broken-in. If it starts to slow down shut it down by pinching the fuel line or pointing the plane straight down. Let it cool completely and start it again. Run it for a series of two minute runs followed by a complete (5-minutes) cool down. Do about 10 of these. When the engine will run a whole tank without slowing down, it is broken-in enough for the air.
This way you can be reasonably sure the problem is not the engine and start concentrating on tank and tank mounting problems.

George