95 grand am. it starts up for 15 minutes then it stalls. and the more it runs the more it stalls. we think its the fuel pump.

Good guess, but first replace electrical plug from car that goes into fuel pump ,on top of gas tank.

You are thinking right.
Try the Fuel Filter first and see if that helps or fixes it.
If not then go ahead and replace the Fuel Filter.
Most Fuel Pump Warraties require a new Fuel Filter.
The Fuel Pump failure is obvious when the engine warms-up (fuel pump is working longer). The longer the Bad Fuel Pump works the more likely it is to stop working. Waiting allows the Fuel Pump to cool down and allows it to engage again.
Let me know if this helped or if you have additional questions or information. Feel free to contact me at FixYa.com!