I have a 02 protege 5. Diagnostics come up with SYSTEM TOO LEAN (BANK 1) and RANDOM/MULTIPLE CYLINDER MISFIRE. I have replaced plugs, plug wires, coil packs, ran slick 50 fuel treatment, and also put new fuel pump,fuelfilter and air filter. Nothing has worked yet. I noticed that it stalls bad and dies when its at 1/2 tank of gas or less. Once you fill the tank up it runs like a champ. Any suggestionson what I might try next?

Appreciate it