Yes, the front O2, the rear O2 only monitors the cat and wont cause any drivability problems. Spark plug wires are high energy wires, and having them touch another wire can cause leakage between the wires. I even blew fuses because I had plug wires in contact with the wiring harness. The leakage will cause odd signals, and the O2 sensor signals are needed to set the AFR. But so far what you describe I'm thinking bad spark. Also check for vacuum leaks. Check around the EGR tube, injector O rings, gaskets, everything. That could explain your idle problem.

Thanks again---more questions for you---what is the AFR? also, what coule be the causes for bad spark? Wires too close together? Bad wire? Fouled plug? I have looked for vacuum leaks, but will look again.

how do I clean the front o2 sensor? Remove and spray with brake cleaner?

any thoughts on the coolant system not building pressure and only climbing to 160 degress? Air pocket somewhere??

thanks again--

AFR is Air Fuel Ratio.

Bad spark can be bad plugs, bad wires, bad coil, arching wire. Take a spray bottle and mist the wires and coil with water when it'* dark, turn off all the lights and watch for blue flashing.

You clean the O2 sensor by taking it out and putting a new one in. sorry, they don't clean well.

Low coolant temp suggests to me a stuck open thermostat. Air pockets would cause over heating or fluctuating temps.

Thanks Dan---You're the man!!

I so appreciate your help and brain, and will keep updating my progress.

One thing that is curious---the car ran perfect before it suddenly hydro-locked. No skip, hesitation or bucking. I wonder what I may have done to cause this new issue. The foulded o2 sensor makes sense, but the plugs are new, and the wires/coils never had an issue before.

More troubleshooting for me!! at least it is running!!

Get the car scanned, there should be some P030X cod(*) Where the X is will be the cylinder number, ie, P0303 is cylinder 3. A P0300 code is random misfire.

Playing another side of the coin here. How dirty does your finger get if you touch the vacuum connector at the throttle body? Those are a common vacuum leak area. Also since you swapped in the new parts big hose from the brake booster to the intake. Double check that and the little nipple off it should have a vacuum line hooked up as well. Double check that there are two o-rings at the pcv. One under it and one at the cap for the map sensor right above it.

The high idle is sounding like a vacuum leak.

Well, new day, new LeSabre updates!!

I am happy to report that the stuttereing was caused by a bad plug. It was bent so bad the gap was non-existant. I was glad to find it. No more check engine light flashing or check engine at all. So, the Buick runs like a champ now even after my LIM gasket and UIM replacement.

However, the high idle problem is still there, around 1100rpm even when hot. I triple checked every vacuum line and connection, and sprayed them all with carb cleaner, but no change in the idle and they all seemed tight. I tried to manually adjust the idle, but it won't change.

My thoughts are like this---the throttle body was quite dirty, black with carbon. Perhaps in the recent repair, when I wiped out the UIM side of the TB I left a piece of debris in there, and it is stuck open a bit. I will remove it tonite and give it a good cleaning, but besides that, I am running out of ideas.

also---even with a new 195 degree thermostat, the car never reads above 160 on the gauge. the system also doesn't build pressure. Perhaps that thermostat is bad, or stuck open. I tried to burp it last night by opening the valve on the therm, housing, and did get some air out, but still it won't heat up. The car has been in the family since this spring and never got hotter than 160 according to my lady. Perhaps these cars run cool and don't build pressure in the cooling system?

thanks all for your help and your site in general. i wouldn't have had the info or courage to do the job I just did without this site and the folks who contribute. Information certainly is power.

Is the seal around the T stat in place? There'* one of two things happening here. If there is no check engine light then the pcm is seeing a temp of at least 160F. Might be a bad temp sensor, in our sensor for temp there are two elements. One for the pcm and one for the dash gauge.

If the system isn't building pressure, it'* time to check the radiator cap. You should have pressure.

Is there a way to test the temp sensor to see if it is within spec? Like disconnect it and connect a voltmeter to it?? i will also look into the cap. Easy enough to replace.

thanks so much!!

More thoughts----

My girl drove her LeSabre last night for the first time since I replaced the LIM gaskets and the UIM. She siad it drove and behaved EXACTLY as it had before the repair. She was thrilled. It leads me to belive that the high idle and low operating temp was a condition that existed before the UIM failed.

The Temp gauge still never reads above 160, and the idle never drops below 1000rpm, even when hot. also, I noticed the fans were both running even when the engine was ice cold??

I found a spec sheet for the ECT sensor, and will check it tonite. I am thinking it is out of whack, or with the fans coming on early it is disconnected or has a bad connection. Am I on the right track??