To all - I am befuddled on what to do next on my 2011 Chevy Suburban 1500 LTZ - I am now getting a P0219A code showing there is an imbalance on bank 1. But here is why I am befuddled - all of what is listed below was done since Aug of this year and frankly, not sure where to go next.

The car has about 165000 miles on it but is very well maintained.

1. Replaced the MAP, cleaned (multiple times) the throttle body, and the throttle position sensor
2. I did have a vacuum leak found after the work in number 1 was done, had a professional smoke test, the leak was found and repaired
2A - forgot this one - at this point, I replaced all of the O2 sensors on both bank sides.
3. This is when I started to get 2 codes - the P0219A and P30301 - So I did the following:
a. removed the fuel injectors - cleaned all of them when powered up and replaced injector Number 1 since I was getting the code on that one
b. replaced all of the spark plugs with top-notch ones (NGK Laser Iridium Spark Plug (IZTR5B11) - but I did not check the gap - they were supposed to be correct (maybe that is part of the issue)
c. Was still getting the P0301 code, so I replaced the number 1 coil pack. When changing the pack, I saw the red wire on the plug into the coil pack was frayed, which I think was the main issue, so I got a new plug and spliced it in and just left the new coil pack in position 1.

It was at this point, I thought I would no longer see any more codes - however I am now seeing the P0219A code again. I have no idea where to go next on this to stop that code or any other code from coming back.

Anyone have any idea on what I should do next, any thoughts or suggestions would be great.
Dave Mc