First I'll start off by saying I've read through a bunch of the threads after doing a search on the 0302 code. I have a 2004 LRD with 104K miles.

Two weeks ago I pulled the oil breather/separator, flushed it with carb cleaner as well as the line and also cleaned out the throttle body.

We just got 6 inches of snow so I went cruising today to play. That's when the CEL came on. Read the codes with the Ultra Gauge,cleared them, they came back on. Sometimes only the 0302 would come on by itself, sometimes the 0300 would come on with the 0302. I thought maybe I'd check vacuum lines since I had some pulled when doing maintenance. After letting it sit for an hour, took it for another drive and no CEL. The Disco's seem finicky, as I've had a 04XX code come on (can't remember what the last two numbers were) and never again. I chalked that one up to the gas tank lid.

I've read it could be numerous things including: coil packs, plugs, wires, HG, etc. Since it hasn't came back on I thought NOT to dig into it but wait til it happens again. It's around 10-15 degrees here and cold plays hell on cars.

I change oil every 3K anarchist style, use Rotella and a Mobile 301 BIG filter. I don't always use highest octane gas, only about every 3rd fill up do I put high octane gas in.