Quote Originally Posted by Fuzzy View Post
It's a 2004 2500 5.9 vin with the c in it. it has 342,000 miles Bully dog triple tuner. Automatic trans. It starts fine but at idle it runs as if it was cold natured (like the old gas engines that need to warm up first) once it temp get up to about 130 are so it smooths out and idles just fine. This what the shop is telling me " when revv'd up it idles down very rough when cold. still shutters on the down even when warm. Rail pressure is normal. Boost and rail pressure was normal."

Yep it comes and goes. Now pulling a load its doesn't happen and when I keep the highway speed down to @70 when boost is low it doesn't happen. I also had the lines changed as well. I can hear the lift running when I first turn the key. Then it goes off. Gelling is been cold but not that cold I'm in La. and South Tx. I do run Lucas fuel treatment every other tank.

Polaraco, Hope ya'll are doing well with all that snow ya'll had.....
I'm just grumpy to begin with. LOL That storm blew past me and hit New England. Phew! Thanks

Is the fuel pump in the tank or on the back of the fuel filter? When was the fuel filter serviced last? You need to read the fuel pressure. I would think the rail pressure would be effected, but it depends on how much air is in the lines. The volume could be low and still maintain pressure.

Get some Archoil 6200 fuel treatment and see if that helps some. If it does help, then you may need injectors. But cneck that fuel pump out first