AU II XR8 Rough Idle and Hunting

[GSN]

G day guys great forum you have here.

First off ive searched through the site and found a few posts about this but ive pretty much covered all the suggestions so far. Basically the XR8 runs very rough and misses at idle and when ur driving along (its auto) and hold ur foot at a constant position (most noticeably at about 1/3 throttle) is will hunt, meaning u feel the car surge forward then drop off. So far ive done leads, MAF, O2's etc and still no joy, its still under warranty but every ford dealer i goto just says yeah its running rough but its not spitting out any error codes. It gives me the %&^$'s because they admit theres a problem but they wont do anything about it. All they do is slug me for intake clean etc every time it gets serviced.

Now does anyone have any ideas what it might be? Also is there anything that might cause it that wont show up as a fault code (mechanical maybe?).

Any ideas would be great.
Is there any good dyno place in Perth that people recommend that maybe would do a good diagnostic run on it, A/F ratio etc that might shed some light.
Cheers,
Brett