You converted it to a 96-00 vintage, which is fine for most aftermarket controllers but not for factory ECMs. I have no idea what an 'eztcu' is but as long as it doesn't require a manual lever position sensor, it's probably fine. The cases themselves didn't change between 93-97 insofar as the worm tracks or pump-to-case channels, just the holes for mounting the MLPS starting with either L95 or 96. The shift solenoids never changed, just the 3-2 control solenoid starting in 96 and the PWM solenoid between 95 and 96+.
I didn't read your first post beyond the title so "forgive" me.
If your data shows the eztcu thinks the transmission is in 1st gear but you're actually in second then something's wrong mechanically, either in the VB or case so be 100% sure of your diagnostics...If you are, time to start digging back into it. First place to investigate is the 1-2 shift valve then 2-3 shift and shuttle valves...It may also be worth vac testing the valve body, particularly the AFL valve...If the AFL bore wear is pronounced enough, you'll also have 2nd gear starts. Also check the spacer plate for anything unusual (stuck check balls, unusual orifice re-sizing, etc). Check the 1-2 accumulator to make sure the seal isnt missing or broken.
Another thing to do is conduct a line pressure test - do that first before dropping the pan. I'd be curious to see if you have unusually low pressures for whatever reason. Again, shot in the dark but these are all things that can cause wrong gear starts.
You built this trans, right? What was the reason it came out for overhaul (most cases, it's the 3-4 clutch pack). Did you notice anything overly noteworthy or unusual on any of the parts when tearing it down/inspecting it?
If I think of anything else, I'll let you know...Interesting case, that's for sure...
Yea, it sounds like semantics but it's an important distinction. To be clear, I'm not criticizing you, just pointing it out in the event others read and get the impression the 60 can be operated mechanically some how... And yes, some of the 2007 model year vehicles equipped with 4L60Es didn't have the turbine speed sensor (TSS). Lucky for those owners; if that stupid TSS (aka ISS) fails, you can't simply drop the pan to replace it.