wmoses, it's hopeless to try to convince others what they already believe or have read in the past... ;)
To everyone else, I've been running a K&N drop in filter for over 12 years and some 190,000 miles and have not had any of the issues that's always stated in these posts...
My 1997 F150 has over 253,000 miles on it now and I got it with 63,000 miles on it, so all those miles since then are mine... :)
I know this started out being a question on DIESEL trucks and I can't comment on those, since I've never owned a DIESEL, but on my gas engine, it's basically the same results as wmoses has, so that's my story.. Your mileage may vary!
Mitch