I didn't mean to derail your thread early on with
@WannFly's inability to maintain course
One thing that could help would be to chair fly in the plane when its not being rented and just work on your scan of the actual instruments. This should not cost you anything at the FBO. Maybe go and do this once or twice between lessons. Working on quickly scanning and then eyes back outside lining up the dash or a speck on the windshield with something outside. While you do this try to get a feel for how much your left hand is pushing/pulling/turning as you scan and return.
I can give an example I have yet to solve. The 182 has cowl flaps. Getting them all the way shut means pushing a lever down almost to the floor. And you have to push it a bit hard as they want to pop back open about 1/4 of the way. Now add that the panel in the 182 is tall. Every darn time I reach down to close the cowl flaps I catch myself turn the yoke slightly to the right and I think I push a bit on the yoke. That one is a bit more extreme than just scanning but its an example of my brain is still moving my left hand with everything else when it shouldn't.
Maybe your instructor could give you a scan order to work on as well.
Maybe someone here could recommend a good scan order for a PPL in training that also works well for instrument training?