2001 Burban "chugging"

Trying to help a friend from a distance and was hoping to get some general info about the 5.3L V8. Without any prior running problems, the rig began "chugging." They changed the fuel filter in the hopes that the problem would be solved, but it didn't help. They were able to start the truck and run it around the block, but it began "chugging" again. Leads me to think sensor issue as the truck did ok in open loop, but had trouble when the computer went to sensor info. I'm also thinking it may be ignition related, possibly. There is a single coilpack and spark plug wire for each plug, correct? Thanks for giving me any pointers. I suggested they go to some parts place and get the codes read, even though the CEL isn't lit. Thanks for any help!

is check eng light on? if runs good cold poss o2 sensor , takes apx 2mins for heat up and see by brain but usually codes . the egr probibly has brain operated vac line that selinoid can cause rpm flux and may not be seen except on real time code readers. you can remove vac line at egr plug and try driving but if this doesnt help you need to give more info.

Thanks for looking in. If I were there I would have had it scanned and looked at codes and live data, but I'm not. The light isn't on. At this point they are swapping the fuel pump, so I'm hoping someone scanned it. I'll post again as soon as I find out more.

Ya hard to help from distance but dosnt sound like pump. But who knows its hard with no codes. The thing is only a few problems dont code, even pump usually shows up as o2 lean.Good Luck helping them

Well, they got it back on the road with a new fuel pump. I'm going to guess they didn't scan it for codes and just threw a pump at it, but they got it fixed. Thanks for the suggestions...

Thanks for posting back. Its good its fixed. still supprised there were no codes?

When mine went out at 98000 miles, I had no codes show up. It was just hard to start, but when it did, it ran normal. That lasted about a week, then it would not fire anymore.