I have not gotten any codes .....yet. My issue seems to be tempeture related. I'm in Minnesota and what seems to be happening is that when it's very cold It takes 2 attemps to start but runs fine. When we get closer to freezing it will start fine but surge when holding steady pressure on the gas pedal.

I have sea foamed the top end, changed out fuel filter, plugs, wires and cleaned the MAf. I'm running a K&N filter. Truck has 95,000 miles All parts are correct and GM's.

At this

 

Make sure the fuel pressure regulator is not leaking, unplug the vacuum line to it and see if any fuel comes out, if so, it's bad. Other than that, you can try to see if there are any vacuum leaks by spraying t-body cleaner around areas where they can occur and see if the engine surges/dies which would point to a leak. Beyond that, w/o any dtcs set, you'll need to scan the PCM's data stream to see if there are any irregularities.

 

Thanks for imput.
Sorry I use a computer at work and it can be awhile before I get back to forum for updates. I've tried the fuel pressure regulator. It appears to be OK, no fuel present. Dropping off at shop(again) to see what the pro's can find. I will get back with update.

 

Long story short on this issue. I had a fuel pump going bad over long period of time. Shop was supprised it ran so well.It had 35psi at start up and around 40-45psi going down the road.
I'm glad to have finally found and fixed ...........but it was supposed to be checked before?? At least that's what I paid for !!

I suppose it may have been ok when checkedby a different shop. I hope it proves helpful for someone else.