All 4 cylinder misfire, what else can it be?

What is your question?

Replaced timing chain, tensioner, brand new cylinder head installed. After this work was done I picked my car up and that day my CEL came on and 9 codes came up so I brought my car back. Shop replaced pcv valve and said runs great when pcv is out but once installed rough idle. Now they are saying its the rear main seal, they've had my car 90 days and ive spent 5k so far on repairs, some I'm starting to wonder if they were even needed. Listed codes below P0300-PO304 Cylinder 1-4 misfire P0011 - intake camshaft position timing over advanced (bank 1) P2279 - intake Air system leak P0506 - idle air control system RPM lower than expected P000A - engine position system performance bank 1