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Hi again. 90 old C/S 3.1. Really bad idle. I replaced the o2 sensor and iacv. After installing the o2 it ran pretty good and then it didn’t. Back to rough idle. Any thoughts on what the issue could be? I’ve heard of bad pcv/ map sensor/ coil pack. The erg is not gummed up. However I just had my battery tested and came back bad. The car starts fine but they said it was bad. I’m not sure if that has something to do with it. Any ideas. Thanks. 

Thanks for the tip. 

Hi, I’ve been experiencing a voltage drop/ surge only when in gear and at idle. I just put in a new 02 sensor and a iacv. And the alternator seems to be charging the battery at 14.2.the car has the 3.1L thanks for any advice!   

Will, the first thing I would say is looking at your pictures the car is delivering a lot of jacking force! This is often an issue with Macpherson strut suspension. I’m pressed for time at the moment, but I will answer your post more thoroughly hopefully tomorrow or possibly Saturday. There are a few things that you can do with the first W-bodies & I have so good things you can do for the W-body ll. 

I've probably put my Grand Prix through the ringer more in the past decade than anyone else on this forum and, at least for first gen cars, I feel the springs are the weakest link for how they handle. My car has the sportier FE3 suspension and the amount of body roll is still really high. I have a few pictures of it during track days while in a corner and while it doesn't look that bad I can say that you really do feel all the weight being thrown to the outside of the car. Braking is similar, you feel all the weight getting transferred to the front wheels during an aggressive stop and I've had the back end slide out from behind me a few times because of it. I think the best way to improve the handling for these cars is stiffer springs and better tires, but good luck finding a shop that will fabricate a new monoleaf for you. This isn't nearly as much of a problem with second gen Ws since those actually have some aftermarket options, but I do have a '98 Grand Prix and still feel like the springs need to be stiffer on those as well. I will also add that I do think dropping the car by an inch or so will help so long as you have camber bolts or some other way to adjust the angle the wheels are sitting at, the center of gravity in these cars isn't that bad but it could be better. Macpherson struts aren't exactly the most adjustable setup, but the tires would really appreciate the weight coming down on them in corners at a better angle.