I think low quality fuel and old fuel could ba a cause to clog up injector.
leaky injector could cause misfire and leaked fuel keeps burning
Then the port gets too hot....etc
just a thought, not exactly sure what had happened
Also at least to my knowledge , my model 05 4runner 2uz-fe doesnt have a conventional fuel filter.
there is a screen on the fuel pump it self.
wouldnt hurt to retrofit a fuel filter