4.0 ECU

You wont be able to 'chip' the ecu itself . cant do that with any of the new ecu's, doubt you will find anyone who has cracked the codes with the appropriate emulator - won't have been much demand so far,

But you will be able to use any of the 'sensor benders' available to do what you want (hks etc. have basic units) or you can go with a unichip interceptor unit, there are others as well . But be prepared for a big spend for the dyno time to do the actuall tuning. Try the usuall intake and exhaust mods first to see if this gives you enough improvement.

thank you very much, thank you for your time.