Bad knocking under feet

but we know for a fact that it's not the driveshaft.
Great Score. Did you have the drive shaft out when checking it? I don't know your skill set but a frozen u joint wont have play in it but has the potential to make a banging sound once driving.Just a thought. Also maybe unplug and cap your brake vacuum booster hose and see if it still stalls out. Just don't get yourself hurt.