I have a '99 Tahoe with a 5.7L V8 350. I had a K&N Cold Air Intake on her for about 6 months, and then she started throwing engine codes. Got my buddy at the dealership to read them and I had a downsteam O2 sensor problem and Low Airflow measured in the Mass Air Flow Sensor. I was told that the oils from the Cold Air Intake can cause problems with the sensors. I replaced the O2 sensor and cleaned the MAF sensor. I also put the stock air filter and intake assembly back on. After clearing the codes and restarting my truck, the O2 sensor error went away but the MAF error comes back as soon as I start my truck every time I clear it. I then bought a brand new MAF sensor and replaced my stock one... still throwing the code every time I start my truck after clearing them.

With the MAF problem, the vehicle shifts VERY hard and can stall while stopped.

If anyone has encountered this with this engine, I would appreciate any input.

Thanks!