Six error codes - P0151, P0174, P0300 codes on each side of exhaust

P0300 is a random multiple misfire. P0151 is a system lean on bank 2 and the P0174 is an O2 sensor showing excess O2 in the exhaust on bank 2. With those codes I would look for a bad vacuum leak or more likely a bad intake manifold gasket. The codes are likely all related to that as the excess air from a leak on one side will cause a lean mix and misfires. It would also cause the other two codes. To check the intake rapidly I would start with a can of carb cleaner and a cold engine. Start it and spray the cleaner around the intake manifold areas, listen for the engine to speed up when it draws in the cleaner. I would try this test first. If you find no leaks then proceed with the next testing.

Another possibility for those codes would be if some of the injectors are not firing from being plugged with old fuel. Both items cause the same result, more oxygen in the exhaust than the system expects. As you don't list any circuit codes for the injectors it isn't likely to be a harness fault. To test that you can do a quick injector test using a pulsing tool and a fuel pressure test gauge.
These videos show the process. The pressure gauge and pulse tool are usually available as loaner tools. One shows using a scope and pressure transducer in place of the pressure gauge but the rest is the same. The tool is shown in the picture, you can buy them for under $30.00 these days if you're local parts place doesn't have one.

https://www.youtube.com/watch?v=K7STocr9FBI
https://www.youtube.com/watch?v=PBt4kOfsX3g

This guide shows the pressure test kit for the fuel pressure:

https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

This is a similar process to verify the wiring to the injector but you are not showing any of the codes related to this testing other than the flow:

https://www.2carpros.com/articles/how-to-test-a-fuel-injector

Once you have done the testing we have a starting point as to which way to repair the problem.