idle not best

300C, 5.7 AWD, 2005, Touring, 6.1 Block, 6.4 Strocker-Kit, Apache Heads with Manley Springs, 228/234 114LSA cam, american racing long tube headers, HJS 200 cell cats (the biggest which fit) 87 mm arrington TB, Fox Catback

My idle is not very stable and always jumping about 50 Upmin (920-870 or 980-930 depending on my setting) and its very unsteady. So my exhaust values at idle are not the best and I have problems with the annual check.My problem is, that our cars are not very common here in Austria/Europe and there are no spezialiezed tuners around my place. In the beginning I got tunes via email from the states and flashed them with a predator, then I found a tuner here which made my car a lot better (he was working with HP) but as I mentioned Idle is still a little problem. I got myself a MPVI and started tuning myself, but this subject is too complicated for me. Trandmission tuning is fine now.
Sometimes the engine even stops and diagnostic codes show missfire cylinder 2.
Anyone an idea what I could change?