1998 Oldsmobile Intrigue car runs hot, over heats

Hello

My car had been running hot under extreme situations, then one day she over heated.I took the car to pep boys; they swore the engine was sound but needed a lower intake manifold gasket. They charged me 700 to fix the gasket and flush the system. Since they claimed this would fix the over heat problem.I also decided to have the air cond. Checked and serviced. Another 200

Within an hour after driving away, the car began to heat up again.I took her back to pep boys, they said it needed a new radiator. Radiator was replaced another 300.

Car seemed to be working, but when I took her on a very small road trip she started to heat up again.

If I run the air or after a long period of driving, she starts to heat up


Please help!

Thank You
Julie