Engine Performance problem
2000 Buick Lesabre 6 cyl Front Wheel Drive Automatic 98000 miles
2000 Buick Lasabre, 98000 miles. When driving the freeway 65-70 mph, going up an incline the engine will occasionally hesitate, not stall, not backfire, but jerk like it's not getting enough gas. If I take my foot off the accelerator for a second and then re-apply it, the action will stop and I don't loose much speed. I've had the fuel filter changed (it was dirty). The mechanics are telling me it's the fuel pump. Could it be the O2 sensor because it starts fine & runs fine on flat surfaces and going downhill and not every incline causes this response. Could it be the fuel injectors? I'm also due for a tune-up @ 100,000 miles. I've owned the car for 7 years and keep up the maintenance as reccomended in the manual. I drive at night in the heat of Las Vegas and don't need to be stranded somewhere.
Inspect and test all the following listed below: Oxygen sensor.
Fuel injectors dirty/sticking.
Mass airflow sensor/Airflow meter.
Throttle position sensor.
Manifold absolute pressure sensor.
Fuel pressure regulator leaking or defective fuel pump.
False air leakage.
Foul/defective spark plugs.
Open spark plug wires.
Ignition coil/Coil packs defective.
Incorrect ignition timing.
Cap and rotor.