1995 4.3L VIN "Z" TBI rough Idle & Exhaust Smell

The engine in my truck is a 4.3L VIN "Z" TBI and I recently had the intake manifold resealed by a GM dealer. Ever since then the engine has idled exceptionally rough and from the smell of the exhaust it is also running rich.

The dealer claims they can't do anything else with it and tell me that "all 4.3L idle rough", but this is something beyond the ordinary and wasn't doing it before I took it in for the manifold repair.

I have also had a tune-up with new spark plugs, throttle body decarb and fuel injection cleaning. I have not replaced the cap, rotor, or spark plug wires.

I need some help with this because I have a mountain vacation planned in one week.

Help & Thanks,
Scott

Check the o2 sensor

Yes the O2 sensor is a good probability, I wonder if they tested the manifold area for vacume leaks after they resealed it though, a vacume leak will definately give you a rough idle but usually it leans the engine out, you can test the manifold area for vacume leaks by spraying carb cleaner around the manifold and egr seals with the engine running and then note any change in idle. Make sure the engine is not to hot when doing this though.