1991 Isuzu Stylus slow?

1991 ISUZU STYLUS
113,000 MILES • 4 CYL • FWD • MANUAL
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CHRISRITTER23
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i have a 91 isuzu stlus that i just traded my dirt bike for..
first off it gets only 20 miles to the gallon.... i have replaced the spark plugs, wires, cap, rotor, air filter, and oil filter... it still gets terrible gas mileage. what should i do about that?

secondly it idles rough and i have taken it to a mechanic and he did a diagnostic and he said it passed with flying colors. it has a new muffler, water pump and radiator.
what about all that?

and lastly, when i am driving sometimes the acceleration dies, it just looses speed and then picks back up, and this happens randomly a have not been able to accociate a consistent pattern, could this be why the car is getting such bad gas mileage? its inly a 1.6 i would assume that it should get around 30+ mpg..
thanks
Chris
Feb 25, 2010 at 4:04 PM
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RASMATAZ
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Hesitation and lack of acceleration:

Inspect and test all the following listed below:

Oxygen sensor.
Catalytic converter.
Fuel injectors dirty/sticking.
Mass airflow sensor/Airflow meter.
Throttle position 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.
Feb 25, 2010 at 4:50 PM