New Silverado owner with questions..

[wesmills]

I purchased a 1999 Silverado 1500 (ext. cab, 5.3L V8 gasoline), and promptly stumbled across this forum while looking for answers on disabling the automatic headlights (thanks! calling R&D on Monday).

A couple of questions .. I'm by no means a car expert, so if this has been asked before and I'm not searching the forums right, pardon my mess..

My truck normally idles at about 350-400 RPM but, without my foot on the gas pedal, will suddenly dip down to around 200 RPM, then go up to 500 or so, and settle back at its normal idle range; all of this for no reason I can pinpoint (such as a hard stop, turning on the A/C, etc). I make the distinction about not touching the gas because it will occasionally do this while coasting in gear (such as turning around in the cul-de-sac at the end of my street) and if I put any load on the engine through turning the steering wheel, it will kill the engine. It restarts just fine, but the sudden power loss bothers me. Any tips on where to start troubleshooting? The truck accelerates and drives just fine, and this problem can happen whether the engine is cold or warm.

Second is that the engine is occasionally slow to start. Most of the time I can hold the key for a second at most and the engine turns over. Sometimes it will take 2 to 3 seconds to start, begins at a very low RPM (100 or so), and works its way up to the 350+ range it normally idles at. There's a distinct possibility this is just how this engine starts in cold weather (30 degree temps around here lately), but could it be something else?

Thanks in advance for all the help..

Wes

[GMMerlin]

Usually a good cleaning of the throttle body will resolve this problem.
Use a quality choke/ carb cleaner (I recommend Wynns Intake Air Cleaner spray) and spray it into the throttle bore, use a soft tooth brush to loosen the deposits on the bore and blade and wipe clean with a soft rag.
There is also a GM technical bulletin on this concern that includes a T/B modification and a calibration update.
Also check the fuel pressure regulator vacum line for signs of raw fuel..is fuel residue is seen, replace the regulator.