I may as well raise my old bugbear: are you using any filters on your lens? If yes, ditch the filter. If no, carry on
Also the Pentax procedure for AF testing involves a FA50 1.4 shot wide open, using Av mode, centre-spot AF, with the target illuminated to EV12, target distance to about 1m (depending on lens of course), and two shots apiece after manually turning the distance ring to infinity, shooting, and then doing same from minimum focus distance.
Except for the EV12, your test seem pretty close to what's kosher, I guess.