Engine shakes

[raul_c_11]

Ok guys heres my story right now. I have a 92 acura vigor (automatic) that has been in great condition since I've owned it. Yesterday when I was driving home my engine all of sudden started idling at the red light. After going a couple blocks down the transmission was having hard time changing the gears. Once I press on the gas it will go fine but when it wants to switch to first gear the engine will shake, but once I release the gas it will switch to 2nd gear and it will do the same for 3rd 4th 5th gear so i don't if its the transmission or not because if it was the transmission it wouldn't switch gears right?? So does anyone have an idea on what is wrong with the car??
Any help will be aprreciated. Thanks.