I am not familiar with your exact vehicle, but on mine I have one under the hood near the firewall, this is the pre-cat bank 1 sensor I am referring to, the other on my car is after the cat, it would not be the one that I think is causing your problem.

1995 and prior, they only have 1 O2 sensor. 1996 and later they have 2 sensors. My 95 bonneville only had one.

I believe the requirement for 2 was because of new new EPA laws along with the requirement to upgrade to OBD2 in 1996.

ok replaced o2 sensor and nothing has changed.. could there be anything from the transmission that could cause issues?

I'm sorry I was not right on that one, it was not a total loss if you were over 100k though, once it runs right again you should have a little better gas mileage hopefully.

Hope you are able to get it figured out ASAP.

I do not know anything about transmissions really, so I cannot help there.

no not a loss cause it did throw a engine light for the o2 sensor. i am gonna pull the plugs and check em.i am gonna take it to a shop that has a fancy scanner that will read it while driving it so maybe ill find out more.

Did you ever find a way to test and see if your cat is clogged?
I think you can unbolt the pipe before the CAT, but if it is a welded exhaust system you may not be able to do that, I know very little about exhaust either, but I do know if it is not flowing efficiently you could have similar problems, but you should get a code if the CAT is not flowing as it should.

Only other thing I can think of is maybe your EGR, the pintle could be dirty, and may be sticking on occasion, if you remove the EGR to clean it you are going to need a new EGR gasket.

Here is some info on testing EGR'*
http://easyautodiagnostics.com/gm_eg...gr_valve_1.php


Having it on a Snap on or Tech II scanner at a shop should be the quickest, and probably cheapest way to figure it out, throwing parts at stuff is not fun, I know from experience!
Maybe you will find out it is something you can easily fix yourself, if so then you could pay them for diagnosing it, then fix it yourself, if it is not too expensive I'd probably let them do since I'm sure their shop could use the business...

i pulled the egr and cleaned it. i am not throwing a code for it. i thought it was the cat at first but i would think it would run like crap all the time not just when it hits operating temp.when it acts up i can put it in park and it will rev to 4000 rpm hitting the rev limiter and will do the same in neutral and for fun i drove it and got it to 30 mph then kicked it into neutral and reved it and it wouldnt go over 2000 rpm. once stoped and in neutral it hit the rev limiter. thats why i am wondering if it is the speed sensor. when in gear it acts up and i guess in gear moving the car could be considered under light load so thats why i am gonna check the plugs.

Doesn't it seem kind of odd that your car can do something this weird, and you're not getting a CE light and a DTC code?

Your spark is OK, you've replaced what sounds like just about everything on that circuit.

Is there anyway '94 and earlier can get a read of MAP pressure and fuel trims? On my '95 with an old Actron 9145, I can get more system values than an Aeroforce can on '96+. But you only need the barest of essentials.

If you can rev in Neutral, your throttle isn't bad. neither are your air coming in and fuel trims unless you stall when you rev in neutral, and you are at operating temp.

As mentioned above, If you are at operating temp, the read on the O2 begins....

but it'* the ECM reading the O2 sensor and running on operating programming, not warm-up programming..

In a '95, if i get a DTC from the ignition circuit like a cam sensor or crank sensor problem, the '95 accesses a completely different part of the firmware. It starts operating in get-this-guy-home-before-he-chips-a-piston-or-worse mode.

If I'm getting this right, the engine runs fine until you try to move the car? Either the trans engaging is reading the ECM something it doesn't want you going over 2K rpms for safety sakes. Or it is all confused and chitting its pants.

What remains is that it seems the ECM should be throwing you some code, if the car is not letting you go over 2K. I'm going to take a wild guess and say that limiting you to 2K is an other-than-normal operating condition, and the ECM should send you some kind of note about it.

All I can say is that I'm on my 3rd or 4th PCM in my '95. When i went to the yard to pull and pay $30 for my #2, I had already spent a month and one at a time cleaned and/or replaced the cam sensor and looked for the stinkin' little magnet, crank sensor, the harness, ICM, coils, battery connections, plugs, wires, and my underwear. Some of them many multiple times as if some magic faeries would it let be fixed through some mystical powers.

When the faeries didn't show up, then I started threatening God and using His name in vain.

It ended by swapping the e-proms and putting in the $30 PCM.

So the car ran great, but I spent the next month or so, expecting to get hit by a bolt of lightening from the heavens.

I tried a speed sensor and no change.. But it did start just stalling in park and it takes a min or two to start it back up.. Going to throw a fuel pressure gauge on it tonite.

well i changed the fuel pump and now the car is fine other than some where i now have a transmission fluid leak..