I see an oil fill cap with a nipple going straight to manifold vacuum, but without a PCV!!! That would cause a HUGE vacuum leak! That could be part of the problem.
Try disconnecting that hose at the oil fill nipple and plugging it up so the manifold can't can't suck air through that hose and see how it runs. Or disconnect it at the manifold fitting and cap the fitting nipple. Usually there's a PCV in that rear rocker cover hole. Like in my picture.
