Have tried it with out air cleaner.
There is a vent at the top of the filler neck. I also tried it with the gas cap wide open.
The 440 Proform Charger has a mechanical fuel pump. I have never put a fuel pressure gauge on it since it runs great.
I have used two different fuel pumps with the same results. As I mentioned earlier, when I take a left turn, not like turning onto a side street but a gradual turn there is a skip or miss like there was an air bubble in the line. doesn't matter if the tank is full or near empty.
Also this engine has never seemed to run as smooth as the other Charger. Both engines built by the same guy.