Have a question about engine vibration.

I have a vibration at idle when in drive. Pretty much had this for some time but has gotten worse lately-can feel it in steering wheel. The transmission support mount was replaced recently but did not help that much. I am not sure if it is engine, transmission, or suspension related. Runs great otherwise. Had one major tuneup and regular maintenance, injectors have never been cleaned. Engine is 4.0 six.