93 3.8L Stubborn cooling problems

Ok guys, i'm new to this board and I'd like to say a big hello to all you out there reading this and take the time to thank you in advance for even taking a look at my thread.

With that said, here's my problem. My girlfriend's 3.8L 1993 Sable is overheating. She first had trouble when it overheated running some errands. She had a busted lower hose so that was an easy fix however, on the busted hose, the end leading to the engine was kind of bloated. The hole was a result of a rupture from that part of the hose so I figured that hose wouldn't be the end of her cooling troubles. I was right...so I swapped out her thermostat...still overheated so I tried taking out the thermostat all together as an experiment and still the car was running hot. I tried a second thermostat from another autoparts store and still no go. There's no more leaks anywhere. The water pump is working fine, and the reservoir is full but through all these steps, the heat is running cold and the car is running hot. I'm thinking it's an air bubble in the system or a clogged radiator or heater core. Does anyone agree and if so, what's the best way to go about unclogging the radiator, the heater core, and clearing out air bubbles.

Thanks

now is her fan tuirning on as well when it starts to over heat? also there should be a bleeder cap or screw before or after the heater core not sure which but usually located right next to the fire wall, to me it sounds like a heater core problem but then again thats just my 2 cents