Need help with the 3.7L

I ran the can in the drive way. It also happens when I rev it up in the upper rpm range. Checked the ignition timming when I replaced the cap rotor and points. Aso went through the carb as well float looks good. The falling on its face I mean there is a loss of power with some sputtering if I put the pedel to the floor it will die if I feather the throttle it will stay running but go no faster than like 45mph. I understand if the tank is dirty it would still clog but since I isolated the tank and it still falls off at the upper rpm range I would think the tank would not be the problem. Aj are you talking about the flaper in the exhaust manifold... could that be an issue?