Fuel injection/idle problem

today i tried starting my 99 auto. xj and it wouldnt start so i charged the battery and it still would not turn over. This was not a problem with the starter though. i tried giving it gas while starting it and it starts right up but right when i take my foot off the gass it shuts right off. i was wondering if this could be the idle control switch and where it is located and how to check it? thanks any help is appreciated.

Idle Air Controller, IAC is on the throttle body, so is the Throttle Position Switch, TPS. Could be either one or both giving you trouble. Seacrh the words, not the acronyms (3 letter acronyms do not work here, but they do work in Google searches with added to search). The testing procedure is in multiple threads here. Takes a $10 multi meter to test them yourself.