Well your still ahead of me, keeping my car running funny seems to be my strong point. lol

I just went and pulled that funky piece off the tranny vac line. its got a large port on one side and a small one on the other. It restricts flow in one direction. Its about an inch long, and has a screen inside of it. --O== crudely it looks like this. I am wondering if some jackass put that stupid thing on there just to extend the hose? No one seems to know what it is, or why it is there. Unless anyone tells me otherwise pretty soon, i am going home and replacing it with a length of hose. If this is a retarded thing to do, or if anyone knows what that piece is for, please let me know asap.
Cheerz!

I believe it is a check valve, I could be wrong tho. My 95 SE has it and so does my buddys 94 SSEi so it must be needed. I had a similiar situation as yours too. Spent the money to have the transmission rebuilt thinking that it was the problem and it turned out to be a burnt #6 spark plug wire and bad coil. Gave the car a full tune-up including a new Delco oxygen sensor, also installed a ported and polished LIM and new APN UIM and gave the car the seafoam treatment and a new oil pan gasket (old one was leaking) and it is running like new now, even gained a few HP.

Its gotten new plugs wires and the coils checked. I checked the plugs like 2 days ago, and they seemed fine to me. I have been eyeballing the O2 sensor for a little while now, I have a lightly used spare i could try and test with, but the plugs are different. The motor was re everything before I bought it. As for the sea foam, iv read TONS about it here, but i have never seen it myself. I'm not exactly a fixture at the auto store if ya feel me. One thing I haven't done is to check the actual wires by themselves. I keep thinking if the plugs are OK and the coils test well, how could the wire be bad.
Thank you for letting me know the other cars had that piece installed. Iv always wondered what it was for, and no one here seemed to know what i was talking about. I thought someone just slapped it in there. lol

I came acoss the burnt wire because i messed up taking one of the front wires off when I was installing the new plugs. I pulled the metal part of the wire off on the #3 wire and when i was on my way to the parts store, my dad pulled out the #6 wire and it turns out it was resting against the oxygen sensor in the back, and because it is heated by the exhaust, it melted all the way through the wire. $1200 for a new transmission when it was just a burnt spark plug wire, lol. I would recommend checking each wire for even the smallest cut or burn. One thing I forgot to mention above is that my car had a similar issue back in November as well, I replaced the crank and cam position sensor because thats what my scanner was telling me to replace, turns out it was the Ignition Control Module.

Well just for information sake, i retested all my coils (top posts only, not underneath) they were each 6.8 or very close to it. The wires are all in impeccable shape physically (didn't test them). Sunday the plugs were all fine looking. The only thing I know for SURE that is wrong with the car, is that there is an external plenum leak that I do not know the severity of. It shouldn't be bad, but with my luck it may be.
The TPS tested smoothly, and i pulled back the tubing on the air cleaner to view the screen on the MAF. Last intake leak I had, you could see traces of anti freeze on it. Its the original MAF from my 1st engine. Anything I should do to the MAF? I was always told to be VERY careful with it, so I am kind of paranoid now.
My car has been through some rough times, and i know i should change the O2 sensor. I'm still waiting on if i can just change the clips to fit, or if i should just get a new one ( i have a lightly used one from a 99 Buick something or other with a different plug).
Its running well enough to get by at the moment, but in 4 or 5 weeks I will have to take a 350 km round trip (about 700km) to pick up my son from summer camp. I hope to use my car, but I mean I'm sure you can tell why I'm concerned now. lol
Peace

Oh, and the spark plug wires are no where near the O2 sensor wires. Now I have moved them even farther!

It wouldn't hurt to go buy some MAF cleaner and give the sensor a good spray, most auto part stores carry it. I'm not too sure if there is a difference between the oxygen sensors used for a 95 and 99, maybe someone else can chime in on that one. Regarding your plenum leak, are you sure no antifreeze is leaking into your motor? I also re-read your posts above and if you are wanting to remove the old stove pipe, you can use vise-grips, thats what I used on mine, and then for the new one, find a socket that fits around it and tap it in with a soft hammer.

The sensors are exactly the same, except for the plug. My plug is long narrow 4 wires a think (....), while the other plug, same wire count, is more like (:. I have both sensors and both plugs, but i don't know how easy or if it would even work to switch ends.
Can the O2 sensor be "cleaned up" a little to see if it improves anything before just buying parts?
Yes, I should get some maf cleaner. I'm not sure if its that bad, but it couldn't hurt. When I unplug my MAF the car stalls, and from what I understand, this is a good thing.
As for the stove pipe, do I twist it out, or just pull it straight up. I have a spare lower intake, but it doesn't mean I want to use it lol.

On the stovepipe, I just wiggled it out, being careful not to make the opening any bigger because it is in there really tight. If the oxygen sensors are the same except the plug, try swapping out the plugs, there is usually a way to get the metal connectors out without damaging them, I am not sure if they can be cleaned or not. If you have a spare LIM, just a suggestion but I would see about getting that ported and polished. I installed a PnP LIM and I noticed a slight power increase, changed the exhaust note just a bit and also saved me 1 or 2 MPG.
The MAF usually does make your car stall if it is unplugged while running, now I have never done this on the Bonneville but on my Olds Cutlass Ciera when the fuel pump was going out, I unplugged the MAF before I started the car and threw the ECM into default and gave me another 200 miles on the pump, lol. When the new motor was put in, did you use the original fuel pump or did you replace it? If it is the original, I would recommend getting a pressure test just to be sure its where its supposed to be.