Tincup,
My 33 did similar things "early on", running Hot Wire Harness with a Grand Cherokee Computer, 08 1500 5.7/545rfe.
Talking with "several others", and received most of the same responses. A friend that is a Mopar Tech at a local dealership asked about grounds. Of course I had the engine grounded to the chassis. His response,"Jim, go stupid with grounds, too many is not enough".
Stupid was: Eng to Chassis, Eng to Trans, Eng to body, trans to body, trans to chassis, no problems since. ?????????
Now, I have a question for you. You added a 2" Mini-Tub, how much wheel/tire did you go with, offset on wheel? I have 17x8's with a 3.25 backspacing and 225R50-17 Nitto Tires on all 4 corners. Getting very close to "on the road" but thinking the 400/450hp is going to want a lil more tire.