I'd call B.S. on the carbon buildup. Not with a truck that new. My dad just gone one of those a couple months ago and he's very thorough about researching stuff before he buys it. I recall him looking at several forums such as this one with people complaining of the same problem. I can't remember if they had it fixed by using a higher octane gas (little spendy right now) or getting something in the computer recalibrated. I do remember however, that some of them said the dealership was very reluctant to give them a straight answer and actually fix it. Oh yeah, all these trucks were '99's also, and it warm climates. I don't go near anything with a wrench that has a bigger computer box under the hood than an air box Good luck.
I've also got a 2000 Silverado 1500 5speed with the 4.3 V6.
Mine also does the clicking noise on occasion. I didn't feel it was serious, but i took it to the dealer anyway. The service manager came out and listened to it with the hood up for a few minutes. He said, "Tim all this is is the injectors firing." He explained to me that the injectors have a little ball inside of them, and when the injectors fire..it's the little ball that i'm hearing. It doesn't do it all the time. In fact, I've got a 98 Ford F-150 V6 at work that does the same thing. The ford dealer said it was noisy injectors, too. Is your truck a V6 or V8? I've had my truck a little over a year now, and haven't had any problems to date..i'm very pleased with it. Hope this helps.
Tim the injectors cycling and this knocking are 2 totally different noises.GM has redesigned the 5300 for 2001 and no longer has the problem-but that does little to help the 99 and 2000's that are affected by it.I use Sea-foam engine treatment,it is only avallable at Napa stores,they have the exclusive to it,you pour in the intake while its running,stall it right out with it,let it set 5 minutes,fire it up.Man ,what a smoke cloud,you will clear the area out in no time.I did this a couple times and my truck runs better now-at least it seems to.My brother has a Caddy that had a carbon problem,the Caddy dealer said to use the sea-foam over the GM cyl cleaner.
I don't have an answer to your problem, but I did want to let you know that NAPA does not have an exclusive on SeaFoam. O'Reilly Auto Parts sells the stuff too. And I can vouch for the stuff as well - it is an excellent product.
I have a 2001 2500HD with a 6.0L and I have noticed, that since the day I bought it, it has a 'tapping' noise coming from the engine. Nothing major, but just something I'm not use to hearing. I assume it is normal for the engines, but I have been thinking about stopping by the dealer and asking about it. I only use regular, but with gas being as dam exensive as it is, I haven't used super yet. Thinking about filling up with super this week and see if that changes anything.
The truck runs fine, but its one of those noises that just seems to get my attention. Only 3k miles on it and its done it since the test drive, so I am assuming this is 'characteristic' of the truck.