Stumbling on Startup

[RTD]

Hello all, I just joined the site and looking for some wisdom.  I recently picked up a 02 Silverado 1500 with the 4.8L.  It was an old plow truck with only 75,000 on the drivetrain which is why I grabbed it.  But since it was a plow truck with all the salt up here it was put through the ringer.  I’ve basically been doing a mini-restoration on it the past few months.  Aside from a ton of suspension and brake work as well as rust wars, I’ve done the following relevant to my issue:

-Replaced the coil packs, plugs and wires
-New exhaust headers and catalytic converters
-New starter
-New positive battery cable
-Cleaned the throttle body 
-New air filter
-Replaced solenoids, filter and transmission fluid
-Pretty much new fluids everywhere except coolant.  No real red flares in the oil when I changed it, just old.
-Battery is good
-Verified the throttle linkage operates smoothly
-The fuel lines were replaced by the previous owner due to rot with rubber ones which look pretty good. I checked the best I could to make sure they all look connected properly but it’s pretty difficult to see in some areas underneath.

 

Symptoms: The truck seems to be choking and running rough on startup.  Some cold starts it fires right away, others it turns over more than expected given all the new parts listed above.  Sometimes once it starts it really stumbles until you give it some gas.  Some warm starts also exhibit the same behavior.  Once it is up and running it seems to be fine, idles smoothly at 700-750 RPM, shifts decently while driving, doesn’t stall out on stops.  The only other related issue I’ve had is when backing up with a full throw on the steering wheel it stalled out.
I was really expecting given the mileage and work I did it would be smooth running but not so much.  Any thoughts?  Thanks in advance and sorry for the long post.
Ryan
 

[RTD]

Forgot to add there are no check engine lights or other abnormal indications/lights on the dash.  Oil pressure, battery voltage both appear normal.

[mjm-1957]

Make sure that the EGR valve is closing completely. The pintle can get loaded with carbon and be held open slightly causing what you are describing.

[RTD]

6 hours ago, mjm-1957 said:

Make sure that the EGR valve is closing completely. The pintle can get loaded with carbon and be held open slightly causing what you are describing.

Thank you for responding - is this something I need a scan tool for your is there simpler way to check?

[mjm-1957]

You can view the pintle position percentage with a good scan tool or just take the valve off and physically inspect it. Just make sure you have an EGR gasket before you do because it can get damaged when you remove it. Good luck.

[Jsdirt]

Also make sure the fuel in the tank is decent, and not ethanol-separated or stale. I'd wager that thing sat around a bit and it's probably borderline. Change the fuel filter, then once you get a few full tanks of fuel through it, add some BG44K to the 4th tank at the gas station before you fill up. That'll clean everything out. Might take another 4 or more tanks after that before it starts running normally again.

[diyer2]

I wouldn't wait to use a fuel system cleaner. 

After it starts/warms up a little does it run good? If so this maybe a cold start issue related to bad sensors.