When at idle, I hear this clicking noise that is very consistent. A good analogy would be the sound at the beginning of the show 60 minutes. When I throttle, it seems to go away.

Does anyone know what this may be? I was thinking maybe low on oil and I am just hearing the valves? When I start, I always see a sooty/oily ash behind my exhaust - acts like it lets out a small bit of oil - is this a valve guide seal problem that is worsening?

I will check the oil tomorrow morning...put in the water and was too dark to read the dipstick.

If you have the 28 Heat, it might be the internal (metal?) flappers that they use in the exhaust tailpipe. I had a Heat several years ago and heard the "clicking" noise at idle only.

It's probably just the lifters. Does it only do it when it is cold? Most GM trucks have a consistent tick (from the lifters) when they are cold.