Just an update on my situation... the problem seemed to get worse and now it's just a misfire. Today while driving the CEL finally came on and I have a P0304 code (Cylinder 4 misfire). I put new OEM plugs in about 8,000 miles ago so I'll check the wires and compression at work this week and see if I can find something. Thank God it isn't trans related.. now I can keep the car

 

I feel the shudder sometimes too, but to me it feels like the tranny can't decide what gear to select. Like when you are traveling about 35-40, and hit the gas to pass, you can feel it down shift 2 gears to hit passing gear. Letting off the gas after hard throttle sometimes does this as well. I think sometimes that the tranny should have been a 3 instead of 4 speed transmission. That way it wouldn't get confused as to what gear it should hit.

 

Any updates? Or did i miss it?

 

You're about 4.5 years behind.

 

So read up to see if gm ever resolved this and a newer updated tsb confirmed it was a bad 2nd hear clutch pack and related parts fixed the shudder/chuggle.

I know it's an old a$$ post but I got bored at work today.

 

I know that this is an old post, but I had the same problem with my buick lesabre. I changed the spark plug wires and it worked just fine. Even if you have fairly new wires, if they are exposed to heat it is possible that they can be warped. Thats just my opinion, which is late for this post, I know.