Just last night my transmission started banging hard into all gears on any kind of acceleration. It gave no warning of a problem, and just 4 mos ago I changed the fluid and filter with no visible signs of a problem. The car has 115k. Recently I took it to Pittsburg and had it climbing hills and so on, but I went pretty easy on it. Are there any sensors that may be causing the issue? It seems strange to me that it was fine and now it is banging into all gears on acceleration. Wouldn't an issue usually present itself with one gear? Thanks for any help!!

Scan it for codes. You may have a P1811. If you do, you can try Billboosts accumulator repair.

When hot in park, check the transmission fluid level,is it on the full line?
The P1811 code adapt long shift can be caused by valve body ECC solenoid sticking or broken, MAF sensor.
You can install a few spacers, rough up the accumulator walls, and or consider the transgo shift kit. My 4T65-e is waiting for a kit right now too.
http://transgoonline.com/products.ph...dcountview=Yes

Don't overlook the fact that it may not be a trnny problem at all. I have twice experienced the clunking feel when my park ave shifted. I was sure I had a tranny going out. Both times it proved to be a problem with thte engine. One time it was a misfire caused by a bad plug wire the other it was a MAF.

As previously mentioned scan it for codes with a good shop scanner.
State of tune or a good running engine, code free, is is relevant to smooth shifting.
The transmission fluid needs to be in good conditions as well. I will now change my DEX 6 fluid every 35k miles. I also just installed the Transgo shift kit for my 4T65E and it does now shift quicker, still very smooth shifts, with no harsh up shifts felt when it gets hot in stop & go driving anymore.

I changed out the MAF sensor and had no problems until just the other night. Back to the drawing board. I have it parked for now. Gonna check out the fluid level and move on to the shift kit if all looks normal. I am having a tough time locating Dex 6. I plan to weld a drain in the tranny pan when I take it apart. I am also considering Sea Foam'* Trans tune before hand to help remove any varnish. What do you think?

You can use Wolf'* Head full synthetic fluid as it is a direct replacement.

Diana, get the car scanned for stored codes. MY Check Engine light never came on yet once I scanned the Park Ave I had P1811 and other codes in there so post back the codes after getting car read with a good scanner.
TransTune will clean up the valve body and remove remove varnish-recommended.
I drove normally with the TransTune in for a couple of weeks before installing the shift kit.
Every thing was clean as a whistle in there.
You should be able to get Dexron VI form any good auto parts store or GM.
I also use only Delco or GM tran filters as well.
When I did the shift kit I started by adding 5 liters then driving and checking levels,I used just under 7 liters and I am on the full line.
I also always use a bottle of synthetic Lube Gard "red" in there as well.
I generally buy 6 bottles to have on hand
Link LubeGard Red: LUBEGARD Automatic Transmission Fluid Protectant