It idles very rough and backfires when in idle but runs really well in rpms higher than 1500. Possible issues are; intake air, air charge or throttle body temp sensor voltage signal out of range. Any ideas on what i should do??

 

In your shoes, I'd start by locating the IAC (Idle Air Controller) on the back side of the throttle body. Remove the small bolts and gently wriggle it from its cavity on the throttle body, leave the electrical connection intact. I believe that with the engine running at idle, the computer should retract the plunger when you plug the IAC port with your palm, attempting to provide the engine with correct idle air.Removing your hand from the port should cause the plunger to extend, trying to limit the idle air. These steps may also kill the engine, which is fine, as long as the plunger is extended when she dies. If not, have a helper shut 'er down at your call and you can clean the entire plunger with the engine off and the plunger extended. Thoroughly clean the plunger and the cavity of any accumulated carbon and crud (I used a 12 ga shotgun brush and swab on my IAC cavity and a fine s/s wire brush on the plunger). Reinstall and check your idle. The book says not to manually pull the plunger out, but people do it all the time. The risk in this practice is pulling the plunger off the rack that drives it (the IAC is a stepper motor).
If you aren't trying to economize and want to remove all doubt about the component, replace it (65-70 bucks).