Thanks for the reply Chico. This task is on my list of exciting car maintenance for this weekend.

I replaced the vac modulator, and it was very straightforward. The trans now shifts more firmly and less mushy and soft as it seemed to before.

I have another question though. Now when shifting the transmission into any gear, the engine really moves a lot in the engine bay. Perhaps as much as 3-6 inches based on just watching it while someone else shifts the car. This seems excessive to me, but I'm not familiar with the setup on these 3.1 liter engines in the N-bodies. Because of the age of the car, I'm concerned about this engine travel causing premature engine or trans mount failures...or something else for that matter.

I'm wondering if I should get a non-adjustable modulator from a parts store and put that in instead of this adjustable one.

Thanks again for all the input on my original question, and thanks for any thoughts on my additional question.

sounds like it would be a motor mount

I concur. The mounts are probably already toast (I wouldn't be surprised if mine were). Also, look over your torque struts (dogbones). I assume it has at least one since GM used the design pretty frequently. It could be worn as well and exists to help prevent the engine from moving.

Thanks for the replies. I don't have a shop manual for this car, so I have to go looking for everything on the car itself until I find it. This engine doesn't have dogbones like on the GP. It does have one mount on the passenger side that has to be dealt with in order to replace fan belts by the looks of it (bummer). This mount is attached to the frame near the passenger side fenderwell.

I'm assuming it also has a trans mount somewhere underneath near the driver's side, but haven't looked for that yet.

As a side note, this car has a strange setup for steering, since it appears part of the steering setup is actually above the wheels and attaches to the firewall. It also looks like CV boots in the same general area. I'll bet it's a real joy to work on that stuff. Hope I don't have to tackle any of it.

Yep the excessive rocking sure sounds like bad motor mounts. When you buy new mounts get the tranny mount as well.

yeah, you dont want to put more pressure on any of them. Just get all new