hi again,
i have a 2004 buick park avenue non-supercharged with 147,000 miles on it. I parked it at work yesterday and my sister came to pick it up later that night and said that it was shuddering when she drove it. I just drove it today, and she is definitely right. First off, the check engine light dings everytime i go over 2,000 RMPS. When the car is in park, it shudders. When i put it into reverse, the RPMS drop to 500, and then the car "engages" again and works. The car has no power anymore, as well as a nasty "old car" sound coming from the exhaust. the engine doesnt seem to be making weird noises when i opened the hood, but something is definitely wrong. Help!!
-Henry

Is the service engine soon light just steady on, or flashing? If is just steady on, probably will be an emission related problem. It does sound like the car is in protection mode though.
More information can be found in your owners manual under MIL Malfunction Indicator Lamp.
A scan for codes will be needed now by plugging into the OBD2 port & view the listed code #*.
Autozone may loan you one for free. Post back the stored codes please..

Check engine lights don't ding, they either come on solid or flash......

Need to read codes......sounds like a bad misfire or plugged cat, or both....

sorry i used the incorrect terminology. The check engine light is FLASHING. i took it into the buick dealership and they said it was most likely a misfire. I dont think my cat is clogged because i have an afetermarket zzp cat on it right now. How much would a misfire cost me to fix??

The diagnostic trouble codes should point to required repairs. Get it scanned, post the codes back here.
The owners manual does state that a flashing MIL is related to a misfire condition.
In the PA a chime will sound anytime the MIL comes on or other warning in DIC is displayed.
When was the last time you did a full tune up from Spark plugs to wires etc?

it has been quite a while for sure. It is at the dealership getting repaired. thanks for your help!

You are welcome! That is what we are here for.
Please post back what parts/repairs were necessary.
This will then help others in the future. Thanks.

just got new from the dealership today,
they said my misfire was on cylinders 1 and 4, and was caused by a coil burning out. So, I had them replace the coil and the wire. After further investigation, they also found out that my module was toast, so they are buying that to replace it too. can anyone tell me where to find a module for cheaper, because they quoted me $440!!!

Well, somebody doesn't know what they are doing.....if you have a misfire from a coil, you swap it to see if the misfire moves...if it does, it'* a coil....if it doesn't, it'* an ICM......and it'* possible the coil took out the ICM, but you should have been told this before with proper diagnosis....

GM dealership? Shame on them....

Rockauto sells them from 100-160 bucks, but I'm sure you can get one even cheaper at a junkyard...there are tons of 3.8'* there....

By the way, last COMPLETE tuneup? plugs, wires,fuel filter, air filter, and pcv valve?

I'm not sure if the dealership is wrong, I am only hearing information in a "dummed down" way so I can understand it. I will probably get a new module from rockauto because i am not spending $400 for it! The last complete tune up has been at least 50,000 miles ago if not more. My grandfather had the car at 96,000 miles and I then took it, so I really don't know if or when he did a full tune up. And, I'm pretty sure the coil took out the ICM with it...