Charles & Sandra Cohen
My memory could be wrong, but I think the AH-4 is a "long-wire" tuner, designed to be mounted at the antenna feedpoint.
I think the AH-4 ATU should be mounted at the feedpoint of the Delta Loop, and _directly connected_ to it. The "hot" terminal to one end of the loop, and the "ground" terminal to the other.
Run coax from the rig to the AH-4. No 4:1 balun needed. You might need a "choke balun" on the coax, at the IC-7000's output.
. . . How close is your antenna, to your rig?
Sometimes, if they're close together, the problem is direct radiation from the antenna, not grounding, or feedling common-mode current.
. Charles VA7CPC