inconsistent knocking in lower engine

A rod or main bearing knock typically gets louder as the engine warms and oil thins. It could also be from oil pump pressure being too low and not feeding the crankshaft journals quicikly enough. One thing you did not mention is the oil filter - was this changed? Sometimes a faulty oil filter can cause flow issues. Easy and cheap to rule out.

try use oil stabilizer to recondition seals and cylinders. engine knock some times caused by air/fuel mix. get air intake and exhaust diagnostic. probable cause off left bank(exhaust configuration creates problems with ignition coils and plugs). use ethanol treatment in fuel tank to clean fuel system. ethanol in modern fuel leaves a lot of setiment through out fuel system.