Problem appears to be solved!
I put the front end up on jack stands last night and went over everything I could think of. Bushings seemed to be just fine, fasteners were all tight, wheel bearings were fine. I mean out of desperation I even checked to see if the sub frame bolts were all present and tight. Found nothing.
Next I put the weight of the car on some 4X6 blocks stacked up so I could still get underneath to see if anything seemed different with the weight of the car on the ground. Still nothing. I was about to give up when an idea came to me. I wonder if the front sway bar is maybe biased right to left. I unfastened the left lower end link heim joint and low and behold I couldn't pull it out of the sway bar hole. I had to pull on the bar quite bit to get it out.
I wound the heim joint in enough to let it slip into the sway bar hole, torqued it down and took it for a short spin. Sure enough... the pull to left under acceleration and pull to the right when backing off is gone! I had no idea that a sway bar would have quite that much influence going down the road.
I'm thinking that between bushing timing and two alignments since putting on the sways and drop springs it obviously is sitting a bit differently than when I originally I hooked up the end-links. I'm not 100% sure I had the front suspension completely settled last night being up on 4X6 blocks so I think I'll have the end link adjustment checked on an alignment rack just to be sure. Also although the pull is gone during acceleration/deceleration now I have a pull to the right going down the road at cruise. I'm sure the sway bar being biased caused the recent alignment to be incorrect so I'll have them recheck the alignment at the same time.
Woo hoo! What a surprise! ... and a relief!
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480 rwhp ERL 416 ci with JDP Stage II Big Bore Cam
JDP tune, CAI intake, Dynatech LT headers, hi-flow cats
VMAX CNC Ported TB. GMPP Z/28 suspension package
Prothane sub-frame bushings.