So what happens while driving, the gas gauge will drop to the bottom, and the fuel light starts to blink, a minute later it goes back to normal

So what is this evap tank? Googling revealed a little bit of info. Have any photos? And how would I diagnose/fix this?

Could it also be the fuel level sensor going out? The wiring on Isuzu's ain't that great from my experience. tranny blowing fuses, intermittent wiper stoppin half way.