Hello everyone, recently my 2003 SSEI Bonneville has started having some weird issues. When I've been slowing down to stop at a light the car has been losing all power. The steering wheel locks up and I have to throw it into Park or Neutral and restart it. It has been doing this intermittenly lately but it seems to be happening more frequently. I've also noticed it seems to happen after the cars had some time to heat up and it alwasy restarts right away after it loses power. I've also noticed lately that when I'm pulling up to a stop and the RPM'* are getting below 1,000 the car will jerk and the RPMs will fluctuate from all the way down to O and back up again almost like its not getting air or something? The other day when I was making a slow turn off a main road I lost all power and had to restart it. I could see how this could be a potentially dangerous problem so I want to figure it out and I have no idea what to do. Any and all help is always appreciated!!!!

Just to summarize what I read, the engine is stalling when slowing down via braking or turning.

Does the engine stall at any other times or does it seem to hiccup at highway speeds?

First, check your fuel pressure. If that'* below 45psi, change the filter and recheck. If pressure is good, then pull the plugs and inspect them. Unplug the MAF, the car will stumble a bit and then smooth out and you will get a SES light. But if it runs better, the MAF may be bad. Check the throttle body for carbon build up.

that same thing happened to me, it was the maf. i would start there.

Billboost..........you got it. The car only will stall or stutter when it gets below 1,000 rpms and like I said the RPMs will jump around between 0 and 1000. It will either stay running or thats when it will lose power and I'll have to throw it in neutral and restart it. It rarely hiccups under highway speeds although it has done it once or twice. I've been told I need a new Catyllitic Converter however I was also told I didn't necessarily need to change it so I've been driving for a couple months with it. Could this be any sort of issue?

Well, I cleaned my MAF and that has not fixed anything. As I said, I've been told I need a new catalytic converter. The check engine soon light will come on, then it seems like a day later it will go off, then a couple days later it will come back on, etc. I've also noticed the car hestitating sometimes when at highway speeds. How would I check my fuel pressure? Any help is appreciated as I've spent over 3,000 on this car in the last year and I'm trying to nip this in the butt. Thanks.

Why do they want to change the Catalytic converter? Is it clogged/broken, or is it not cleaning up like it should? If it is clogged enough, that may account for the issue.

Well I had a "Check Engine" light come on and when I got the Codes read at my local shop they told me that I needed a new Catalytic Converter. They said unless the car was running badly they didn't recommend changing it as it is an expensive repair. Well fast forward 2 months forward and now I'm having the problems I have described in this thread. The Check Engine light, as I mentioned before, will continue to come on and then go off. For instance, yesterday all day when I was driving it was on, then this morning I drove to work and it has been off all day?

Sounds like the cat, but get your codes pulled. Autozone does it for free.

Sounds like the torque converter is having problems locking and unlocking. I have a 2001 SLE that is doing kinda the same thing. The tach is moving up and down about 500 rpms while coasting. At times it goes all the way down to zero and stalls the engine. It always restarts. Have been putting off the repair cause it is going to be expensive.