Severely underwhelming K-3ii

I don't know what is going on with your gear and nobody knows until we see some photos.

I could aimagine a few things:

1) your camera is not calibrated very well. I tink we can send each Pentax camera once for free check at the official service (I know this offer from Germany). Maybe you should do it - maybe send the lenses, too. So they can adujst your gear and you have best you can get.

2) I could imagine wrong use of the AF system.

You know setting a camera to AF doesn't mean that you simply press the release button and get a sharp photo? You have to half press first to let the AF do its job - and next press full to make the photo. If you use IS you would have to wait until the hand in brackets in the viewer appears - this means the camera sensor is stabilized and ready for shooting.

3) Which expousre times did you select? The K3ii is a camera with very high pixel density on the sensor. The consequence is that a very little moement of the camera will shift much more pixel than if the pixel denisty is lower - and you will get more blured photos from it - but IS system can help - and also much shorter exposure times. The generel ruel is max exposure time is 1/focal length - but you should at least select the effective focal length of the APS-C  which means focal length of your lens x 1,5.

I am sure you will learn to know that you can get impressive photos from you K3ii. DonÄt blame the camera before you did not find the reasons for your problems. I am sure the people on this forum can help you to find them.

Best regards

Holger