Even when it's warmed up after a short drive it does this?

First I'd make sure the MAF is clean

 

I did have the upper intake blasted to eliminate the carbon build-up, but there was no change.

 

You should probably still check fuel pressure and hook up a scanner that has live data and misfire counts. Sometimes a misfire doesn't necessarily trigger a CEL.

Injector balance test would also be something to do, maybe one is faulty at idle only.

 

Yeah, something is going on when the pressure is lower, I just don't know what it is.

 

vacuum leak

 

What year truck? Is this truck new to you? Is this your first V6? It will never idle as smoothly as a V8. Put a tune on it and raise the idle speed to 650 in drive and in park.

 

2017. It was fine at an idle before, so I am not sure why its a issue now, but not before.

 

Remove and clean the throttle body.

 

Blasted the carbon out with the crushed walnut carbon cleaner.

 

I guess you have three options as to what to look into first your diagnostic tool will determine how easy that is for you. Fuel air electric.

Other folks said before definitely check fuel pressure and monitor fuel pressure with truck running and see what it does when you reproduce the issue. If you check out at the rail, your fuel pump is fine.

I do an injector balance test. All injectors, equally balanced, and look good. You probably fine there too.

Any funny business with the sensors obviously you’ll need to read some live data and see what reporting back. Fueltrims and O2 sensor readings will help you determine if the truck is running lean or Rich. if you graph and monitor the readings of other sensors along with that to see what is consistent with the condition it may help you narrow it down. Could be a misfire too. Solid diagnostic tool will let you monitor all of this.

 

You should be doing a fuel induction service once every 30k. Direct injected engines need it done every 15k cuz they do not have fuel washing over the intake valves. Add a bottle of techron every oil change and get an oil catch can amd change the pcv it will keep oil out of the intake tract which causes deposit build even faster. I have a 2019 silverado 1500 with di 5.3 have an oil catch can and change the oil every 4000 miles with full syn. Add techron every oil change to keep the fuel system clean and it also helps the pistons to stay clean. I do a fuel induction service once a year and normally when I do it on customer vehicles and my other vehicles I get alot of smoke out the exhaust from it cleaning all the crap out. We'll with the truck I get little smoke and only for a minute or 2. The valves are clean as new same with inside the intake manifold and the pistons because of the catch can, oil changes on time, and fuel system staying clean as well. Bg products I used at every dealer I've worked at its top of the line stuff. Do a fuel induction cleaning with seafoam the spray kind they have or crc intake valve and turbo cleaner. It will clean the intake manifold, throttle body, and intake valves and pistons. Replace the pcv valve as well which should be changed every couple years.

 

Any updates to your rough idle situation? I have a 2017 Silverado and am experiencing the same issues. No codes been to 2 shops and the stealer, the last shop said its the motor mounts. Which they probably need changing but I can't see motor mounts causing the tach needle to fluctuate with the rough idle. Maybe im wrong though.