The Autometer Electronic Speedometer was playing havoc with the VSS signal of the transmission when connected per Autometer instructions. I disconnected Speedo and tranny worked like a charm. I thought it might be vss sensor but with a new sensor in it, did the exact same thing! At this point i thought it might be a ground so I disconnected speedo entirely and reconnected using it's own ground, power & light source and vss signal and NOPE, same thing erractic tranny shifting!
So for the time being, it's a bad speedo...
2008 2WD Ext.Cab Silverado 1500 6.0 V-MAX E38(L76) & T42(4L70E) MAF Only CL Corvette Servo AFE CAI INNOVATIVE LM-2 WBO2
FLASHSCAN V2 & AUTOCAL