Newbie here, posting for my less internet literate father...
He's got a 2001 GC with the standard output 4.7L V8. For the past few months its exhibited a surge/flare at engine start. He claims it is under any start/restart condition, although I have not observed this personally (I live 8 hours away).
I've done some research online, it seems like the 99-00 models had a reflash for this. His vehicle is not covered by this reflash, and it only started recently (at 6 years / 60k miles). He's had the IACV cleaned and inspected, I'm not sure what else is causing it. Bad water temp compensation? I've seen something related to idle that is caused by a bad CKP, but this isn't idle its startup. He has not complained about idle trouble or poor performance other than startup.
I apologize if this is a common issue that I should have been able to find info for. If you guys have some insight, we'd appreciate it.