I've had this issue with the Miata since I've owned it. On occasion, when coming to a stop, I'll stall. I've read on m.net and other Miata forums and there doesn't seem to be a consensus on the issue, other than throwing a bunch of parts at the wall and seeing what sticks.

It happens hot or cold (engine temp), using the brakes or not. I thought maybe I had a vacuum issue when using the brakes hard, but I've come to a stop using the transmission, and it'll do the same. I've read everything from debris in the gas tank, to replacing the alternator. I've already replaced most of the vacuum lines, I still have a few to get to, but I haven't done anything else to address this. Just figured I'd post here and see if anyone has any other ideas.

I've had that problem with my car. Most of my problem turned out to be play in the throttle body. Basically it was so worn out that it would close itself off and stall the car.

Does it sputter and stall or does it just shut off?

I could probably tell you what it is if we could recreate the problem on a drive.

Do you have a lightened flywheel? After I switched to a featherweight flywheel, it was common for my car to stall when coming to a stop (when depressing the clutch) since my rpm's dropped so quickly. Now I just blip the throttle a tad when stopping or downshifting.

If that's not your problem, then your "DFCO" may be out of whack.

No lighter flywheel yet. There are also times it doesn't stall, but RPMs dip REALLY low, then return to normal idle. There are no idle/start issues at all. Once it stalls, it fires right back up with no problems at all.

does your car have a dashpot?

Just looked it up and it does have one. I would start with that.
http://forum.miata.net/vb/showthread.php?t=149192
http://www.miata.net/garage/ignition.html#idle
http://forum.miata.net/vb/showthread.php?t=211005

I'll doublecheck when I pull the car in the garage for some work. I did do the dashpot stuff a year or so ago and it didn't make a difference. Doesn't mean I did it correctly, haha.

Let me know what you find out, because mine does the exact same thing.

Mortose wrote:Let me know what you find out, because mine does the exact same thing.

Maybe I could take a look at yours since you are closer.

I do know the 1.8s don't have dashpots, so that's one fundamental difference. I don't think it's the problem on my car, though.

What I suggested to Mortose was to check his IACV (or ISC as Mazda calls it). Don't know if he checked it and what he found though.
Just jumper TEN and GND together and drive it for awhile and see if it makes a difference.

Seems to be another common point. I'll try that out.