1995 Oldsmobile Silhouette

Engine Mechanical problem
1995 Oldsmobile Silhouette 6 cyl Front Wheel Drive Automatic

On flat it drives smooth no loss of power.
But soon as we start up a hill power level is very low.
EX.45miles but soon as we get half way up the hill it drops to 10 miles and we try to put it on drive 2 and over drive and still no real power.
I did the basic on the car,
Gas filter, oil filter, oil, spark plugs and wires, air filter.
I even check the fuel injection and O ring and they are fine.
I check the are carb and thats fine too.
I am lost now.
August 26, 2010.

Lack of acceleration, chugging, hesitating, bogging, misfiring etc. Could be caused by one of the following below: Oxygen sensor.
Catalytic converter.
Fuel injectors dirty/sticking.
Mass airflow sensor/Airflow meter.
Throttle position sensor.
Crankshaft position sensor
Knock sensor
Manifold absolute pressure sensor.
EGR Valve
Fuel pressure regulator leaking or defective fuel pump.
False air leakage.
Fuel contamination.
Foul/defective spark plugs.
Open spark plug wires.
Ignition coil/Coil packs defective.
Incorrect ignition timing.
Cap and rotor.

Note: If it doesn't apply disregard it.

Aug 26, 2010.