[p00t]

There is a lot going on here so I may have missed something...

Verified timing chain is on there correct? I know you took the head off but you have two chains to deal with. Low vac on stock cams is often because one of the chains is off a tooth.

Have you tried disconnecting the MAF just to see how it runs? You have to start it twice without cycling the key to off with the MAF unplugged. I am not sure if there are any tight bends in the piping before/after the MAF (which is going to F-you).

If all that checks out look at your tune. Specifically the balance between latency and K value. What are you using? For idle that is lean keep increasing the latency. I don't care that you think 1ms of latency or what you have is too much, if it is lean keep increasing!

Once that is idling in the neighborhood of 13-14AFR then work on your K value. and keep going back and forth until you are happy. You will likely have to deal with a richer idle so that you are good in cruise and boost. Stock injectors are very linear in how they behave, as you go bigger the low pulsewidth stuff is just shitty.

Also before you change anything else in the tune TURN OFF O2 FEEDBACK. It has never worked right for me with bigger injectors.