Deaf-
Is the K&N filter that you have an OEM replacement? Or is it the kit where you now use a cone shaped filter? On your tank question (not that I am an expert in Cherokees...yet), my Haynes maual says the cherokee came standard with a 13.5 gallon tank and has a 20 gallon optional tank (although I think in later production years, the 20 gallon tank became standard). I see nothing in the book about a 16 gallon tank (unless it's a 20 gallon tank with 4 gallons of debris collecting in the bottom).

1998 Cherokee Sport/4.0 L H.O./5 speed manual
Bitchin' stereo/modified seat to fit my long legs
Considering off-roading acessories before vehicle upgrages