Here we go again....

I went 4 wheeling up past Ballarat in South Panamint Valley, CA (pictures soon) here's a link that's close to the trip we did.
http://away-home.tripod.com/manson_barkerranch.html

Well, it was very dusty on the trail but I can't imagine the K&N filter getting clobbered on one trip. I started the truck up a few days later and it feels like it's missing a cylinder or the timing is off. Tonight I got a check engine light. Anyone have any advice other than what the manual recommends (take to dealer and pay gobs of cash).

Thanks,

Vern