Q: My car doesnt want to run correctly when the AC is on.

Bought the car 3 days ago. It was kind of shaky so we did a tune up. I put in the Autolite platinum spark plugs, new oil and filter, and lucas stop leak and stop slip transmission oil because it was very low. After all that the car didn't even want to drive. So we reset the computer by removing the battery and later turned it on. we got it out into the driveway and the car didn't want to accelerate. It stayed stuck it doesn't even automatically shift. It won't pass 30mph. My gas went down half a tank by testing it out around the block. So we stopped driving it. the next day I put my windows down and backed up and starting driving with the ac off and i stepped on the gas slowly and it started shifting again on its own. But it still feels a little forced but not like before. When the AC is on it is even worse. But with the AC on or off it still won't accelerate normally. I have to accelerate slowly and let it catch speed. I have no idea what the problem is.

My car has 101700 miles.
My car has an automatic transmission.