I just installed a K&N FIPK on a 1997 F150 4x4 Auto. Now when the Truck decelerates it drops Idle real bad and sometimes cuts off. I have done some searching and have not found an answer. We also reset the battery twice. The only other mod is Magnaflow Catback.

 

Alright we talked with K&N and they said disconnect battery for 2 hrs which we did and then she said it takes about 150-200 miles for the computer to readjust. Hope this helps someone in the future.

 

check for any loose conections it sounds like you have a vacume leak, good luck

 

Been there done that.
You have put too much oil on the K&N filter and it has contaminated the MAS.
With a little luck you can use a good grade of electrical cleaner and spray the MAS sensor. Other wise it will need to be replaced. The other possibility is that the sensor has become un plugged. remember there are two sensors in the air inlet tubing.

 

We did not put any extra oil on it. It comes from the factory preoiled. We gave it about 100 miles with out doing anything to it and it runs like a champ now.