P0300 code help

[Neo2020]

2000 Pathfinder 4wd auto. 167k miles.
Background: Car runs fine. But I did notice on the highway around 50 mph it seems to lose power. If I floor the gas it will pull and continue to accelerate normally. Starts up fine, idles fine. Did have a b2s2 code but changed it out and now have a p0300 soft code. Ran the car and got a p0304 but only because plug 4 was not tight enough. Fix that and now the p0300 code again. Changed plugs, wires, cap and rotor, cleaned TB and MAF sensor. Still getting p0300 soft code? Don't seem to have any leaks that I can find. Here are some details from a freeze. Can anyone tell me if anything looks wrong that could be causing the code. Don't know where to look now.

FT B1S1 -11.72%
FT B1 short term -11.72%
FT B1 long term 0%
FT B2S1 0%
FT B2 short term 0%
FT B2 long term 0%
Intake air temp 78.8F
Intake man pressure 4.3511 psi

O2 b1s1 0.83v
O2 b1s2 0.79v
O2 b2s1 0.05v
O2 b2s2 0.01v

Boost & vacuum gauge -10.49 psi

[04pathse]

fuel filter might be the culprit, try changing it and see if that does the trick.

[Neo2020]

forgot to add that I already changed the fuel filter also. I do get a flashing ses light on the highway around highway speeds. Flashes for a few seconds then goes out. I also seafoam the gas tank at about 3/4 tank. Currently the ses is off but still have p0300 soft code pending after driving about 45 miles. I don't want to keep throwing parts in if I don't need to.

[MisterH]

I'd probably test out fuel pressure/rate-of-flow issues.

[Mike W.]

Since bank 1 is rich and bank 2 is lean it's not something in common with both of them, such as fuel pressure/flow, unless a fuel line is crimped or the like. Looking at the O2 readings Bank 1 is very rich, even after the ECU leans it out, and bank 2 is lean going off the O2 numbers even though it shows 0 correction. But it could be the opposite of what you think. It could be a cylinder on that bank is very rich, the O2 sees that and leans it out.. O2 readings while immensely valuable can be confusing and sometimes seemingly contrary to what you expect. It all makes sense if you think about it long enough, but sometimes you really have to chew on it a while.

But focus on something bank dependent, a large vacuum leak, a bad injector, a hose cracked or off. Might be a cylinder, might be the side, but on one side not the other.

[Neo2020]

I checked all hoses for leaks but can't seem to find any. Also I'm getting a p0171 code as well now. Both 0300 & 0171 are soft pending codes. They seem to alternate on refreshing the scan or both come up at the same time. No SES light though. Very weird. Still getting the lose of power at around 50-55 mph only! 0-50 runs and Accels fine. 50-55 feels like I'm letting off the gas. If I press the pedal down it will bypass 50-55 range and go back to normal.