1992 Buick Century number of things

Transmission problem
1992 Buick Century Front Wheel Drive Automatic 107866 miles

ok so I was going to practice 25 miles from my campus and I was on the freeway going about 50-60mph cause traffic was bad and slow. I decided to take a side road since it seemed faster, however after driving 10-15 mins I came to a stop light and started slowing down (i didnt brake hard or anything) but once I pushed the brakes the car started jolting and lugging. Then I coasted through since the light turned green and I pulled into a parking lot. The car died once I stopped, but when I was slowing down to stop the engine was making I guess best way to describe it is "clunking" noises and then more jolting. I let it sit for about 5mins then restarted it and the engine raced. As if it was in neutral and your pushing on the gas. But I was in park with out pushing on anything. The engine then calmed down adn idled for a bit and it seemed fine, so I started drivng again. I went for about 3 more miles before having to slow down again it did the same thing lugging and jolting. Then died.I but it in reverse and it seemed like the gears didnt change for it go into reverse and it was having a hard time backing up. Then it seemed to click in and reverse fine. I then turned around and headed back to campus and didnt make it back cause every time I braked more cause I had to stop it seemed like it was getting worse, so I just had my roommate pick me up. After waiting for my roommate I tried to test drive my car around a parking lot and it was having a hard time going around that and was lugging so I stopped. After about 20 mins or so of waiting I drove again around the parking lot and across the street to a gas station and it was fine. I checked the transmission fluid and it was fine, my engine oil is good and so is my coolant. I had new brakes put on last may and also a new intake manifold gasket. IDK wats going on. Either tomorrow or today I am taking it in to car quest to have them look at it. Oh and after the sun set and it cooled down I was able to drive my car back to campus with my roommate following me and it drove perfect. But driving on the freeway and then having to exit and slow down is hard and it always does the lugging. Ps it started doing this about 2 wks ago but it never died, last friday was the worst. Any more information needed let me know