JDM ep3 misfire when cornering. Water in fuel tank?

[ShelfWobbler]

The car has been without issue for years but has recently developed a strange misfire.
The misfire occurs when the car is cornering, particularly when cornering at low speed for example turning into a junction. The misfire soon clears once the car straightens up again.
I've plugged the car in and there are no codes, no eml light has been displayed either.
When checking things over I've spotted the fuel filler neck is in a bad way. It looks like water has pooled where the rainwater drain has been blocked (car is kept outside in "summer") and corroded through the neck.
Do you think it looks like water has been making its way into the fuel tank? See images below
And would water in the fuel give me these symptoms?

 

[Hazz]

Certainly looks that way. Never seen that happen before. However, water bring heavier than petrol you’d likely not be running at all… try syphoning it and see

 

[ShelfWobbler]

Thanks, I'll get it booked in for a good looking at.

 

[ShelfWobbler]

I can confirm it was water in the fuel, it came out looking like milk after it had sloshed around the tank on the way to garage. Running well now that the tanks been drained, cleaned out and the fuel filter and filler neck/cap has been replaced.