I don't hold out much hope that the MAF will make a difference. Reason being is that if the MAF is unplugged the idle doesn't improve, when it's plugged back in and I start the car it will then idle higher on the rev gauge and its worse. It would be useful to know what a car without my issue and the MAF unplugged ran like!

I thought it was a vacuum leak too which is why I had the intake manifold removed, the throttle body out (and cleaned), a new PCV, new rocker cover gasket, new intake manifold gaskets, a new purge valve etc. Are there any common hoses that split on these or a way to help find one?

Either a hose has split and it's not been found or it's a fuel not a air issue but then the injectors have been done and there are no codes.

Also, there is the subject of the chain. It might be out.