tuning experts in here

[scooter k]

I'm new to this but here is the problem I have. Mostly at idle in gear after sitting at a stop light for 30 seconds or so my truck starts to idle really rough.
It can better be described as loping or surging. It will do this for maybe 10 seconds and then snap out right out of it. When it starts I see my wideband start to show leaner and leaner until it somewhere around 18-19. Right after it quits the wideband shows 12. Doesn't do it every time but will always do it on a cold start where you start it drive it for about 2 minutes and stop while in gear. Can anyone take a look at the log and my tune?? It is at the last part of the log at about 2.45. Vehicle is a 08 Chevrolet Silverado 6.0
Thanks for any help.

[Mep_q8]

what mods are on the truck? sounds like u might need some new plugs..

[scooter k]

Cam, LT headers, CAI, stall, etc. I never have any misfires and doesn't act like it's missing at all.

[Ben Diss]

Sounds like it's doing an emissions test.

[DSteck]

Sounds like it's doing an emissions test.

+1 I'm assuming the rough running part is at the very end of the scan... You can see the PCM command a lean AFR, and then command rich before commanding stoich again.

[slow67]

Could it be the Catalyst Test or the Post O2 test?

[scooter k]

+1 I'm assuming the rough running part is at the very end of the scan... You can see the PCM command a lean AFR, and then command rich before commanding stoich again.

Yes it is at the very end. What can I do to fix this?

[scooter k]

Should I go ahead and disable both tests?

[DSteck]

If you got rid of your cats, disable cat overtemp protection (assuming it's enabled).

[scooter k]

I've still have cats but they are dynatech high flow cats. Can I still disable it?
I looked and my catalyst and post o2 sensor tests are still enabled.

[LBSBLOWN]

scooter k did you ever figure this out? my 2008 Yukon Denali is doing the same thing and it does it on the stock tune so I think it may be a componet issue like the O2 sensor except that the EMC is commanding thoses AFR's.

Any way i am working on the same problem and was wondering what you found.