I have these three codes...

P0304 (121 MILES / 62 MILES)
P0404 (430 MILES)
U1024

2004 GMC 2500HD DURAMAX (LB7) w/ engine surges approx 50 -100 rpms at idle or at stop light, worse when truck has been running for at least 30 minutes.

any suggestions???

Thanks.

P0304=Cylinder 4 misfire detected
P0404=EGR open position performance

Go to the top of the page and click on "User CP", fill out your signature so we know exactly what mods you have done to your truck...

Sorry about that, just bought the truck so I need to do some research, I will get the needed info...

Thanks...R

Truck has a Western Diesel Kit w/ exhaust installed. Can't find anything else that is not stock at this time. Thanks for the help.

Search the LB7 threads for "surging"...Seems like a faulty fuel pressure regulator is a cause of this...Let us know what you find...