Ok, so I got the transmission on my 2011 LT rebuilt at a local shop and saved a lot of money from the initial quotes from the local mechanic and the dealership. Thanks for all of the feedback and help there.
Time to deal with an issue that was there even before the tranny issues popped up.
When I bought the LT, I was impressed with the peppy engine compared to the 08 LS. However, that was when it had 60k miles and now with 130k *and actually since around 100k), the peppiness is gone at low speeds. From a green light, I can press the gas halfway down and it will creep forward for half a block or so. If I mash the gas there will still be a delay, but it will kick in a little quicker. At highway speeds, it will quickly go from 55-75, but that low speed acceleration is getting annoying, borderline dangerous.
No CEL. No codes on my OBD scanner. Air filter changed at the last oil change. Nothing snagging the pedal (carpet, rock, etc.).
Thoughts?
MAF? Throttle body? The actual pedal?
Thanks.

 

Maybe a compression test is in order.

Throttle body inspection seems easy enough to do.

 

What does your scan tool show while accelerating? Load, TPS, MAF etc

 

Sounds like you lost 1st gear or a torque converter.
Maybe clogged cat?

 

Clean the MAF
clean the throttle body
if they are already changed , spark plugs.. AC Delco 41-103 iridium!
is the timing chain loose? If you haven’t change it yet.. time to investigate
seems simple but how is the air filter?

 

Yeah, my wife suggested that, but like I said it was doing this before the transmission trouble, and it's the same after the rebuild and they checked everything out there.

 

I haven't checked that. I am using Torque in Android. What should I be looking for?

 

^^ This. ^^

Clogged cat would not give good high speed acceleration. IDK about the torque converter.

 

Has it been getting worse over time? If so, the cat is likely getting plugged. A back pressure test may be in order.

 

A clogged catalytic converter will eventually throw a P0420 code.