Burning Lean - NEED HELP!

I need help on this one! I've got a 97 F-150 w/ the 5.4L and it sat for about 4 years before I bought it. Now I have done a complete tune up (wires, plugs, PM, O2 sensors, ect.) and it still has a check engine light. OBD-II reads that its burning lean, and besides that it SUCKS on mpg. Any Ideas? Im not a rich person so i dont want to shoot blindly.

Thanks John

Do you have a K&N air filter?

If so, throw it out, and get a standard paper filter.

Then, clean you MAF sensor, located inside the air filter housing. Remove the two "tamper proof torx #20" screws, carefully pull the sensor out, spray the two wires off with "nonresidue contact cleaner", and reassemble. Also, remove the negative battery cable while doing this.

Do you have a CEL?