i35 P0301 Rattle & Misfire HELP!

[PossiblyCorrectJames]

Hey everyone,

My Car: 2002 Infiniti i35
Problem: misfire and rattle. (See video link below)

What I have fixed:
New spark plugs
New Coils
Timing chain replaced 10,000 miles ago.

Note:
The car seems to run a bit better on high octane fuel with flue injector cleaner.
Current code is p0301 and it's constant. I have had p0300 two times.

Any thoughts?
Intake? Injectors? A sensor or something?

Any input would be greatly appreciated.

[youtube]https://youtu.be/hy67JMq4bAM[/youtube]