Bad idle

I have had my 2001 Silverado 5.3 for 10 months and it has had an occasional bad idle since I bought it.

I will be sitting at a light and all of a sudden the idle will drop down to 300 rpms. Sometimes when it is cold it will die when I turn the wheel. The idle always seems to be low in this truck, but it is only rough when it drops below 450rpm.
I have thought about replacing the spark plugs and wires and also the o2 sensors....any suggestions?

Also check fuel pressure (should be 60 PSI). Fuel pressure regulators are known to leak but check the pressure first.

//2000CAYukon

Try a throttle body cleaning (about $100 at the dealer). Most of the 5.3L seem to need this every 20-30000 miles. Symptoms are usually a stumble while stopped in gear. Though it might not be your problem, that'd be a good place to start. Also put in a new fuel filter while you're at it.

If it's been a while, go ahead and do plugs and wires. If that doesn't take care of it then, I'd check for bad vacuum lines. Easy to overlook, but can cause an assortment of strange maladies. Get a can of carb cleaner and spray it around the vacuum lines and connectors. If the engine revv's a bit, you found a leak.

EDIT: Perhaps check PCV too.