OP, you have a 4L60E/80E not sure where DynamicEFI is on trans these days- I know one of those later TBI ecu's was very versatile and could even do a version of mpfi. Do the later ecu's even have...

There you go....I didn't recall seeing that item.
Anyway you tried to help me awhile back and it was appreciated- I would like to think I'm a little further along now. I don't enjoy tuning it's...

http://www.dynamicefi.com/

Flash2, probably best bang for buck, Robert has several bins that may be close to what you have, budget WB O2- BUT steep learning curve. Next vehicle remains stock for...

Dave W- are you familiar with EBL?