Stalls under deceleration 96 Deville

[tackleb0x]

Decided to start my own thread to separate out some confusion. I kind of hijacked someone else's who was having a similar problem, but its quite different.

The only codes I had were o2 sensors so those are replaced about 2 weeks ago. No codes have come up since. Correction: Code came back up PC0147. No other new codes.

Here's what I posted after replacing the O2 sensors:

Cleared the codes. Still occasionally drops to very low RPMs when down shifting around 30mph but the engine but hasn't died yet and still no codes. Maybe the new sensors are adjusting fast enough and i'll be fine. It wasn't shifting hard its more the sudden change in RPMs that I feel. There was only o2 codes so I was pretty sure it isn't the transmission. We'll see. Its kind of weird, I've never had a car do this. Love the car and just want to enjoy it.

Where I'm at now:

My deville often drops RPMS way down when down shifting I would assume from 4th to 3rd at 30MPH. This sudden drop in RPMs:

1. Doesn't happen at all when the engine is cold.

2. Doesn't always happen when the engine is hot.

3. Doesn't always kill the engine when it does. About half the time it adjusts quickly enough and the engine doesn't die. Seems better since replacing the o2 sensors, but I'm also alot better at hitting the gas before it dies and avoiding going under 30mph.

4. Always starts right back up

5. If I drop to 2nd gear (on the shifter) on slow city streets, I've been able to avoid the problem. (Still testing)

Couple questions:

1. What sensor is the PC0147? I thought that was B1S3. I replaced B1S1 and B1S3.

2. If its B1S3, what would cause B1S3 to throw a code again?

3. Is there a way to get it to run like it runs cold? Would unplugging it default to how it operates while cold? Regardless of emissions.

It uses some oil. More than I would like to see but I heard its normal. Its about a quart per 1000-1200 miles. I'll keep better track of this going forward.

Thanks!