I just got a 2000 Tahoe about two weeks ago.
It's bone stock right down to the air filter.
It has 5.3L and only 46k miles on it.
My problem is: at startup it has a poor idle.
It only idles at 500rpm to begin with and the the poor idle it drops to 200rpm then catches itself and revs to 800rpm.
The problem seems to happen more at start up, but I have also noticed it at a red light.

I'm going to check the fuel filter this weekend. Any other ideas?

 

My first guess would be the throttle body... I'd probably pull it off and clean it out nice and good.

My truck does that when something is up with my IAC motor due to some poor tuning by me. I have a feeling your TB might be gunked up with carbon or other junk.

 

Good advise...start with the TB and IAC valve.

 

Check the fuel pressure regulator also if you're experiencing this more after a hot soak. Pull the vacuum hose off of it and see if fuel is present, if so, it's ng.

 

Thanks for the input.
I will check the throttle body and the fpr.
Seems to happen in some for all the time, so I'm banking on it being the throttle body.