Ah, that makes sense. I just found out that an engine just out of long term storage might not idle well either. Just this weekend, I got my 12+yr old OS .61FS running again. It's been in storage for around 10years. The first flight, I wasn't getting much power, and the idle was pretty sad. I was worried I was going to have to tear down the engine (something I usually try to avoid). But after the 2nd flight, it was running as well as I remember it ever running, with a much lower and more reliable idle.

So, I'd give the fox more time good luck.