I know this is not necessarily an appropriate place to ask this, but I know the brain trust in this forum is unmatched. My nephew fell off the roof and wound up in the hospital, and at the same time their Suburban they use as their main transportation started giving them trouble. His wife is trying to get it fixed. They're in Alaska with a large family, so they need this rig to run right. Here's their Facebook plea. Since the engine has so much in common with Corvettes, I thought this was a good place:

I got the suburban back from the mechanics. It was running better then started acting up again. It will surge in idle when it is warm and when you put on the brake to slow down or turn it wants to die. When the engine is warm and you put it into gear it wants to die. We now know that it isn't the spark plugs, wires, distributor, rotor, fuel filter, vacuum leak, idle air control valve, throttle body, or the ignition timing. The mechanic thinks it might be a computer sensor going out. If anyone has other suggestions please list it here so I can pass it along to the mechanic. The rig is a 1994 chevy suburban k2500 5.7L 350...Thanks

 

Our 2003 Denali XL had similar issues. Surging idle, wanted to die, ran like crap at various times etc. Our issue turned out to be the intake manifold gaskets - unmetered air getting into the big 6.0 confused the computer to no end.

 

Thanks for the quick response, I've posted that to her FB.

 

I had to tighten the bolts on my 1996's intake because some were loose enough to nearly turn by hand. This seems to be a problem with a lot of engines with plastic intakes due to very low torque specs. I don't know if the '94 had the plastic intake, but it's definitely one area to check.

 

That was it - thanks so much, guys!

Here's what I posted:

Great - glad to hear it's fixed! And it wasn't me - it was Heather's great description and those geniuses over at the Corvette forum. I swear, those guys know everything.