01 Grand Am Horrible Gas Mileage

My Daughter bought her first car from a reputable used car dealer and has nothing but problems. She has put more in to repairs than payments. Our main issue right now, is that she is only getting about 14 MPG. We have put in a new Fuel Pump, Fuel Filter, O2 Sensor, and routine oil changes. She has issues with it dying out when she is driving, and puts on the brake to slow, it will shake/shudder and then die out completely. It starts up great, idles great, only dies when driving/slowing down. We have detected no leaks under the car (gas leaking). We don't know what else to tell our repair shop to look for. Any ideas would be appreciated. With the price of gas - she is going broke on the car!~!!!:2cents: :2cents:
I don't know the engine specs - it is a 01 Pontiac SE1 4D.

Welcome to AF.

I would say 14mpg is unacceptable with this new of a car.

Its pretty easy to find out what engine you car has, says it right on top of the engine.

Typical excess fuel usuage could be a dirty air filter, low tire pressure, a fuel leak(check around the fuel filter-"O" ring in there can get damaged when replacing), clogged/dirty fuel injectors, or some other fuel system components.

Anyway, try replacing the plug & wires if they havnt been.
I'd also suggest a full fuel system cleaning.

Hope that helps.