isuzu rodeo on lpg

hi there
can anyone please shed some light on this problem for me.
i have a 2001 frontera mx which is the same as the isuzu rodeo in the states and have recently put it on gas.i have a problem with the check engine light coming on all the time which i've been told can be fixed by using the right emulator eithier from the injectors or o2 sensors or both.can anybody tell me which is the right emulator and do i need both.it also has a problem with coming back down to idle rpm's when you take your foot off the accelerator.i've been told by the installer its because of the electronic throttle on the vehicle which is also controlled by the vehicles ecm.can anyone tell me wether the right emulators in the right places will fix this problem also or is this another seperate issue altogther.hopefully someone out there can help me.
thanks