I ok, I seemed to be confussed and concerned on my next step. I have read about a better MAF and the bigger throttle body or the computer chip upgrade.
I have a 98 Mercury Mystique. Auto tranny
2.5 Duratec . KKM air filter. SHO Y pipe and Dynomax Muffler.
SO what should I do next? and WHY?

Its not what You buy,
Its what You build!

98 Mercury Mystique 2.5 Duratec( my wife's car)

87 Toyota Supra Turbo
475Hp at the rearwheels( my car )