My 19 Tahoe generally runs great. Has good plugs, air filter, etc. I notice when I first drive in my neighborhood, there seems to be a little roughness. Once I get on the main road and drive a couple miles, it runs perfect. I know on my older 04 that there was an issue with the intake gasket getting hard and leaking when cold but when warm, it wasn't an issue. i wonder if this is an issue with newer 5.3's. Any ideas?