My 2002 saturn boils over but does not overheat sometimes i will drive across town and all is fine sometimes i will drive 7 miles and reservoir will boil over.im guessing thermistat water pump or cap

I agree, if it's boiling over, then it is overheating. It sounds like your coolant isn't mixed correctly, or it's extremely low. Your coolant ( also called antifreeze)should be a mixture of 50% water, and 50% coolant. If your mix is mostly water, it will overheat. No matter how well your water pump, thermostat and radiator cap are working. If your coolant mixture and level are ok, it could be a thermostat, water pump, or even a radiator cap. The radiator cap raises the temperature that your water/coolant will boil. I would look at the thermostat and radiator cap first. You can test the thermostat if you like, but it's almost just as easy to replace it. Plus, they're much less expensive when compared to a water pump. Same thing with a radiator cap. Very inexpensive to replace.
Please let me know how things are going.
Tim

Of the water is boiling them it has run hot. There is no way around this fact. Get a compression test done first. This should reveal if any damage has been done. Then address the boiling off problem. This can be a air pocket in the line, incorrect anti freeze mixture, sticking thermostat, water pump, cap, etc.