Very rough idle on '97 Tahoe

[budbowl7]

I would appreciate any help/advice people can give me on my struggling Tahoe.

I've got a '97 2D with the 5.7L and just had it at the dealership because I could not get it start up-completely dead when I turned the key. They traced the problem to a bad ground and also replaced the starter relay. There were also error codes with regards to O2 sensors but they said that those were just related to the bad (ungrounded) circuit so those weren't bad.

When I got the car back, it had a terrible idle. It would cycle through idling down to the point that it almost quits out and then it would rev back up to almost 1000 RPM and then come back down again and almost die- this would just happen over and over again. It died a few times today when sitting at traffic lights and it will die if you put any kind of load on it like turning on the A/C compressor.

My question is #1) any ideas as to what may be the problem here? #2) Does it seem as though the dealership could be at all responsible for this or does this seem purely coincidental considering the work that they were performing. Any help you all can give would be very much appreciated.

[budbowl7]

Well I was able, through the help of others, to diagnose the problem. It turns out that I have a blown intake manifold gasket, pretty bad too, on the backside of the engine closest to the cab. This is the gasket for the upper intake, though, and not for the entire intake manifold. Anybody taken off just the upper intake before? I'm considering doing this myself, but I don't want to get in over my head. I was just looking for any input on how difficult a job this is. Thanks.