TBear. I hope this works out for you soon.
I also had the same issue and for the new members that asked what is happening, I had the same problem. (Pics posted on the link below.)
In my case I knew it was an issue and thought I'd give it a try to see If I could get lucky. No dice. Mine showed severe backfocus problems. In other words If you focus on a spot and the lens actually focuses 2 inches behind the spot, you have backfocusing. Front focus problems are the same but the opposite effect.
It didn't matter whether the lens was focused on a close subject or one far away. The image looked soft, even when stopped down.
Having shot Pentax for more than 25 years and used a number of AF bodies, this was the first time I had seen this issue. But you could tell right away even without doing any testing. And I've owned more Pentax glass than I care to admit to...
Anyway the camera was set up on a tripod and at the measured 45 degree angle at about 16 inches from the test sheet. 2 sec MLU was used to eliminate jitter and the shutter speed was more than high enough.
You can see from the test shots that the lens had a serious focus issue.
So I sent it back the very next day for a full refund. Next lens will be the Tamron or Sigma Macro to cover this range or if they admit the issue as Tom said and come out with a DA* 16-50 f2.8 VII model. I wouldn't touch this on the used market with your money let alone spend my own. These will be relatively worthless on the used market IMO.
Test/sample pics:
http://pages.google.com/edit/Islandviewsphoto/pfposts?authtoken=bcd312cf9a0f...0faaa303f4238a