I have been hunting down an engine management computer for my Jeep project. The stock Jeep computer is not easily programable, even the tuners are just add on modules that intercept the sensor signals and adjust them.
I finaly found something that should work, I havent looked at all of the systems, but most have the ability to customize the fuel and timing maps, and even tune individual cylenders. Very flexible systems. Some even have the ability to have multiple maps for different fueling modes. They are a bit pricy though at $1000+.
DFI
Haltech – Engine Management Systems
TEC³ - by Electromotive
MoTeC > About ECUs > Overview