I would stop looking at little things and start looking at big things. In my experience little things will shrink groups by 1/2" maybe a little more and give consistency. You seem to have a "big thing" problem.
1) Are the stock screws torqued down (as in tight, I don't mean are they 5 lbs off from what you thought they were), you said you changed scope did you check that the base screws are tight.
2) Is there a crown problem
3) Did you have some type of "bedding/fit" problem occur
4) Try a different bullet, significantly different in weight, like in the 115 to 125 range
5) Use the OCW load devlopment method