Diagnose cluster: misfire, surging(?) and codes

Hi all, I need some help with my 2010 third gen.

First problem, hard acceleration pulled a p0304 (cyl4 misfire) and p3190 (I assume poor power). Pulled the manifold and cleaned it, then the knocking started.

Sat for a week, thesis to write. Pulled injector 4 (inc intake up to throttle body for space), gave injector a squirt with some carby cleaner (not a proper clean by any stretch) reinstalled, went for a roll. No difference, knocking, difficult, rolled straight to auto shop, bought injector cleaner.

Dropped enough in the tank with 1l of fuel, burned up and down a big hill several times. Checked OBD, pulled:
P0304 (but it hasn’t come back since, perhaps cleaner did the trick?)
P0701 - too lean
P0401 - insufficient exhaust gas recirculation flow.

So, I burned up the highway a bit more, especially along some massive hills, then the engine started - and I don’t know what the correct terminology is - hunting? Surging? It would just softly bounce off the rev limiter, probably 3-5k in 2 second cycles.

It’s still a bit rough at idle and starting up to push off. If I stop, sometimes the engine doesn’t which is completely out of character. Position into ‘N’, no aircon, engine stops as a rule. Not now, sometimes just keeps running for a minute. If I accelerate hard and it feels like doing it, the engine will start it’s bouncing. Poor student, please help.

 

thanks. 450km/280mi. I cleaned the egr cooler about 20k ago, cleaned the pipe and manifold together this time as well.

Can I test the fuel pump before I remove it?

 

Would low fuel pressure explain the knocking and ‘surging’ problems?

 

Ok so an update on my ex taxi with 440,000kms. I went though this car and changed the fuel pump, injectors, spark plugs, cleaned manifold, cleaned egr and valve, tried a bottle of liquid head gasket, new mass airflow sensor, nothing worked. Was PCV. Is now throwing a P0420 code so I’ll go down that rabbit hole starting with the front O2 sensor.

My PCV symptoms were rough idle, almost refusing to shut off, and the engine just revving in this weird 2 second cycle where it would bounce up to the rev limit and back down to about 3k. This would happen until up to temp and would drive fine enough when driven gently around town but if I went on the hwy, off we’d go again.

Now chasing the O2 issues because fuel consumption is bad and the P0420 code is up.