I've had so much done to my truck lately its hard to tell what is affecting what... After it threw those codes (41 and 42) I took it in and they took care of everything...new plugs, wires, distributor, O2 sensor and a tune up. Now that I got it back I've been having this weird problem... When I'm sitting there in gear but with my foot on the brake (like at stoplights) every once in a while it'll feel like something engages, the truck doesn't roll forward but you feel it shift a little (exactly like when when you put it in gear from park)....so that has been weird and I can't figure out what it is... Then today when I was going through the drive-thru it was taking a loooong time and it was idling the entire time...after about 10 minutes it shut off....I popped it back in park and it fired right back up so I just cleared it out and it was fine.... Here is my question...what is your idle @ when you are in gear just sitting there w/ your foot on the brake? Mine used to be at 500 and I never had any problems with this "jerking" or with shutting down...now its at 350-400...which I guess is enough of a difference to have issues...so is 350-400 too low?