Idle Problem

[96ss1664]

I have a 00 3/4t suburban with a 6.0L, in park with the engine warmed up it idles at 1000 rpm it has NO SES code, it has idled like this the last two days. So tonight I unhooked the battery for 5 minutes hooked up and the thing is idling back around 600-700 rpm like it always does. What could be causing this, could a faulty TPS do it?

[96ss1664]

Well its starting to effect my tranny now, my tranny shifts harder now from 1-2 and 2-3 seems like it constintley shifts at the same point in all gears 2500 rpm?

[ChevyTech007]

You need to have this scaned for codes before anything else.