For some reason the PCM or powertrain control module is sensing a shift timing issue and/or low line pressure and ramping the pressure up, it's a fail safe mode that's there to keep it from slipping and destroying itself. Without a code scanner that's capable of reading the transmission side it's near impossible to tell what the actual issue is by a general description alone. There are numerous sensors that feed the computer and most are linked via software with the engine sensors, any one of these can put it into a fail-safe and the only way to know is with a comprehensive OBD-II reader that will cover not just emissions related but powertrain as well.
The 4T65E in my 2003 LS will go into a similar fail-safe as the pressure regulator solenoid has rubbed itself a rut over time that holds it up until the computer commands otherwise and it will start hard shifting, hard enough to chirp the front tires on the 1-2 shift. I've learned to live with the issue knowing it's protecting itself and I manually control the gears by hand shifting while letting off the throttle, not the most elegant but I don't have the time to pull the side cover off. Allowing it to bang shift hard will eventually beat up the CV joints so in your case I'd recommend a professional, you didn't mention if it was a 4-speed or the 6-speed automatic. Regardless of what you have do not have it "power flushed" no matter what the sales goon recommends, the 4-speed has a removable pan while the 6-speed is a unitized case with no pan. With mine I used a cheap electric "auto pulse" type of fuel pump to suck the fluid thru the dipstick tube with a length of 1/4" ID PVC tubing then refilled with new, drive 30 mins to pump it thru the torque converter and do it all over again until I went thru the gallon of trans fluid. I'm at 235+K miles now.

 

'11 will have the 4-speed automatic. 6-speeds began in '12.

 

Wasn't sure when the 6-speed came about. As for the present issue my money is on a hung up pressure regulator solenoid.

 

Unfortunately I simply don't have the time or resources to pull the side cover and valve body at the moment, definitely need to replace the pressure regulator solenoid and the drive chain.

 

Shift kit just gets installed from pulling the bottom pan.
There are a few parts that go in the side cover, but you don't have to use those.
It's the one to two and two to three accumulators.
Different springs and spacers said to give it quicker shifts, which will eliminate the max adapt command from the computer.
I'm getting ready to put one in mine.

 

Unfortunately I simply don't have the time or resources to pull the side cover and valve body at the moment, definitely need to replace the pressure regulator solenoid and the drive chain.

TBH not a job I ever want to do at this stage in my life
Looks like about a BI(%& of a job.

 

50k is roughly the right time to do your first drop the pan, replace the strainer, and change the fluid service.
Change the original strainer out with either the Wix or the OEM. The OEM pan seal is reusable. Do not use the gasket that comes with the Wix strainer. Be careful to make sure that the seal on the strainer pick up tube isn't stuck up inside the transmission.
If the 4T65E pan magnet TSB has not been performed you need to pull the pan and do it.
50k is a little early for noticeable wear on the PCS plunger but iron filings from the chain poisoning the electromagnet can make it perform erratically.

The TransGo kit is really straightforward with the bottom pan off the 4T65E.

Here's GM TSB 08-07-30-040C

2010 impala LT weird transmission shifts

So I have a 2010 impala I bought about a little over a month ago and it wasn't do it at first now I'm geTting weird shift points. On a light acceleration I get a slight pause on 1-2 but a kinda harder pause/shift going 2-3 going into OD is smooth like it's suppose to shift. If I give it a...

www.impalaforums.com

Don't buy any super fancy whoopdedo fluid just get something that says it is Dexron 6. Not "Dexron 6 compatible"... Dexron 6.

 

I bought the car around 6 months ago from a dealership she only had about 57k now she's at 59k. After a few weeks of driving the car and settling in i can feel the transmission switching gears and sometimes from 1st to 2nd feels a bit rough or stopping and going down like a busy interstate where the car has to go from 1st to 2nd alot it can feels funny. I'm not mechanically inclined but something feels off it's not all the time but there's little signs that are worrying me. I've done some research and I think it may be the transmission solenoids sensors gone bad and need replaced. I've also thinking about doing a trans drain and refill because its the right time for it.

I'm not sure what to do if the transmission is going bad or if its normal for these cars? I should of done more research because common issues states transmission problems but my car hasn't even reached 100k should i get the transmission checked? or replace these solenoids everything else is great on the car but hope i dont have to get rid of it because of the trans

Pull the stick. If the fluid is not cherry red change it. Some idiots NEVER do this. Clueless. I do mine every 30K.