QX80 P0011 and P0300 after installing ignition coils

[moshmasterx]

Vehicle Details: 2014 Infiniti QX80 AWD Deluxe Touring Package. ~125k miles. Excellent service history, recent oil change, oil is clean and levels good.

Background (I THINK THIS IS IMPORTANT): Starting about 3 months engine was very slightly rough when accelerating uphill around 30-40 mph. The SES light came on with code P0420. I changed the upstream O2 sensor and code went away and the engine seemed to smooth out, but to be fair the roughness was so subtle it is difficult to be certain. Last week the SES light came back on with the same code and the engine started to get rough again. I had read that bad ignition coils could have a similar effect. Considering the mileage I decided to swap them all out. After doing so I started up the vehicle and got a code for misfire in cylinder 3. I checked the wiring plug and sure enough I hadn't snapped it all the way in place. Then when I started the car the idle was very rough and the engine would cut at 3,500 RPMs. I then get codes P0011 "Intake Valve Timing Control Performance Bank 1" AND P0300 "Random Multiple Misfires". I double-checked the coils and connections and didn't find anything wrong so I had it towed to a shop since I was now fully in over my head.

Shop Response: The shop reports that none of the cylinders on bank 1 are firing. The mechanic states that the coils and wiring are functioning properly, although I think they may have simply done a visual check that the wires were connected. They have also said that the Variable Valve Timing Control Solenoid- Bank 1 is functioning, but again I'm not sure they checked it thoroughly. They now want to start tearing down the engine to check for timing issues such as the timing chain jumped, or there was a cog tooth issue etc. which of course comes at a substantial cost.

Question for the forum: Considering the order of events a legit problem with intake timing seems unlikely. What, if any, other possible explanations should we consider before opening up the engine?

Thank you for any help!

[VStar650CL]

Pull plugs on Bank1. Given the P0420, you may have sucked in the cat.