HI i was wondering about the fuel injection systems on YJ's and TJ's I live at 6000 ft and regularly drive to up around 1000ft on paved roods so i was wondering how the jeeps FI systems deal with altitude change how easy they are to tune for more power or engine upgrades  

The ECM (engine control module)takes care of all this so you don't have to. As far as upgrades go most engines benefit from a better air intake and exhaust system. You might contact an off road shop in your area (altitude) for their input on what works best there.  

so as far as after market parts the ecm will addapt to the changes with out any re tuning.  Is there any way to to tune a stock engine for more power with the ecm or are the older ecm on the YJ's not tunible.