Engine Performance problem
1998 BMW 318 4 cyl Two Wheel Drive Automatic 141000 miles
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the engine lite is on but seemed to run fine until this a.m . at 3000rpm it only runs about 20 to 30 mph and jerks alot. the computer read out diagnosed an injector port to small possible air pump problem. air pump? a freind said it may be the mass air flow sensor.at 6000rpm it really runs bad and only 40mph. start with the sensor? thanks

Have the faults read out and repost with your findings. I need to know exactly what the problem codes are.