the best I can tell was there was a leak in the complete fuel pump assy/housing. I replaced just the pump cause it was alot cheaper (3 in fact), fuel reg, and a bunch of other things that I can't remember. I even tried an in line check valve. Once I replaced the complete assy the problem went away. the car started acting normal with the exception of the gas gauge not reading full when it was. then the ignition switch was getting stupid and had to disable the passlock. then...I sold it and bought a nissan. LOL.
Also a pit fall to stay away from is spraying carb cleaner down thru the plastic chamber that goes to the throttle body. I did this several times without a problem. then one time I sprayed it real good and she wouldn't start so the wife and I went to dinner. came back and tried to start it and BOOM!!!! the plastic exploded into pieces and landed 50 yards into the back yard. So don't do that. I spent the rest of the night putting it back together with rtv and aluminum duct tape.
I had my car since new. It was a great (too strong...OK) car. Then it started leaving us stranded too much. the problems were weird. just weird!!! So that is when we got a Nissan and all my problems went away. When it breaks it is something that is stright foward that I can fix. Which has only been once. And I knew that it had this problem when I bought it. That was why I got it cheap.
Good luck with the devil alero. they can be a real bear to figure out.