WZ Fiesta misfire like symptoms

[Ben228]

G'day all,

I've got a 2016 WZ Fiesta (1L ecoboost).
In the peak of COVID-19, I filled up with E10 from a Caltex servo. I was on empty and the other pumps were unserviceable.
As we know, fuel stocks were sitting around for a while during that period.
So long story short I think I got dodgy fuel full of water.

Car started running like a dog. Misfiring under load.
I've gone through about 5 tanks of BP ultimate 98 and it had gotten better, but still seems to be there.
I've tried adding an octane booster, and I've also tried adding Metho to the fuel to try and absorb the water.
But I can't completely get rid of the 'misfire'.

My question is, is it possible that the plastic diaphragm Re-circ valve has split? I've heard that's common.
Or is it more likely I still have water/dogdy fuel?

What should I do from here? Drain the tank dry? Fuel filter? (not that I've been able to find one)

I'm running out of ideas.

Thanks in advance!

[fiestaz]

Spark plugs?

[Ben228]

I'll pull them out and have a look.
Car only has 32k km on it, I'll check the condition and gap at the same time.
Thanks mate!