U My 98 k2500 threw a p0175 code on the way home from work today. There seems to be a correlation between that code and k&n filters on the other forums. I've had a k&n for about a year now with no problems. Also have hollowed out cats for about a year. Anyone else run into this problem? I'm going to try cleaning the MAF sensor and the filter when I get the chance. I'll let you know if that makes it better. Any other suggestions?