You should BOLD your edits... makes them easier to spot
even better would be to actually post them up instead of editing your previous post ( if you are asked for more info ) This way we know you replied.
I also have a '93 SSEi, and I can beat on it pretty severly and still nail at least 280 - 300 miles per tank ( full tank -- about 1/8th tank )
You also should change your fuel filter, air filter, O2 sensor, PCV valve.....
What plugs did you use?
Any check engine lights on?
Check all vacuum lines
What does your boost gage read at idle? how about wide open throttle?
There are a TON of things that could effect mileage.... lets start narrowing this down
If possible, look under the car and trace the fuel lines.... is there any chance you might have a leaking fuel line?