I have a 2005 chevy tahoe with the 5.3 in it. when you first start it up it idles like it has a big cam in it, but as soon as the engine warms up it idles fine. runs fine no matter what. my brother works for a chevy dealership and said that the number seven injector was dirty. he cam down and cleaned injectors and tried it and it didnt do it after that, but the next day it started doing it again. anybody else have a similar problem?

 

My 04 has a nice bop, bop, bop out the tailpipe until warm, I've heard a few suburbans start up in parking lots that sound the same. a little lopey when cold. I did some Redline fuel system cleaner with no change and have been doing Lucas cleaner since, I buy that stuff by the gallon and use it in all my cars w/ fuel injection.

 

There is about a 95% chance that it needs intake gaskets. That is almost the exact symptom. Once the engine is warm everything expands and seals back up