5.3 with excessive crankcase vacuum and sputter

I just bought a giant turd with a 5.3l on a stand alone harness. I am having problems with it sputtering so bad it wont even move when its cold. Once its warmed up it runs OK but feels low on power. I ran codes with a cheapo scanner and it gave me a PO405 and a PO452 which should be emissions codes. EGR valve and fuel tank vent.

It also has a lot of crankcase vacuum, like you can barley get the oil cap off. I wanted to see if anyone has a diagram of all the vacuum hoses as some are plugged, some are open, and some run into each other.

what year 5.3L is it?

what is it in? where are you located?

Our test engine had excessive vacuum also.
Pull the pcv hose and block the intake side.
Fixed.
Btw the oil cap would be tight and whistle with all that vacuum.