Driving it off the cliff

[blue62]

Vacuum leaks can cause misfires but your codes are for just bank 1.
So I would look for something that would affect vacuum on just one bank..
General or common vacuum leaks are going to affect both banks.

First thing I would do is a vacuum test with a standard vacuum test gauge at idle.
I would look to see if it pulls vacuum within spec.
But more importantly I would want to know if there is any action from the needle.
You want a steady needle like it is painted on the gauge face.
If the needle ticks that "could" indicate an issue with valve timing.
Which could cause misfires.

That is where I would start as a first step it is a simple and cheap diagnostic test.
It could "possibly" tell you if the issues is related to valve timing or not..
If it tests out good with a rock solid needle then valve timing is good.

Then I would look for other sources of vacuum leaks on that one bank.
So something within the intake system on that head.

Also the electrical wiring to the coils and the injectors.
I think the last two are unlikely mostly because misfires are affecting all three cyl.
Possible but unlikely.



Also did you record the freeze frame data when the codes where set?
It would be interesting to know the conditions when the codes set and if they set under the same or similar conditions every time.