I have a 1992 Century with a 3.3L V6, 3 speed automatic with overdrive that starts and idles fine when cool, however, after about 15 minutes, after the engine reaches operating temp, if I have to slow below 30-35 mph it stalls, although 2 footing gas and brake sometimes works.After the engine cools down, about 30 mimutes to an hour depending on outside temp it will start right up again with no problems for the next 15 minutes. On the interstate with no traffic it will keep running, but seems to be rough or missing. After it warms up, while idling in Park it will be running rough, (loping, or missing). I haven't checked anything specific, I would like to know the best order to check possible problems. Fuel pump does cut on with the key, but with the problem only happening while engine is warm, I doubt this is a cause.
Any help appreciated!
Cheers!

Clean the throttle body and IAC. Also, would be nice to see what the ECT is. Do you have a scan tool?

I don't think it will accept a scan tool, I used a jumper wire on my ALDL to get codes from the blinking "check engine" light. That showed no codes at all except for being in diagnostic mode. Tapping the electrical box on the MAF didn't make the engine stumble or die.
The engine is multi-port fuel injection.

The ICM & CKPS can both be heat sensitive. When the engine stalls, do you have spark to the plugs?
3.8L Ignition Module Test and Crank Sensor Test (3X, 18X)

not sure, I'll check tomorrow after I clean the MAF. Hopefully that works. If it doesn't, then I'll have the perfect opportunity to check that.

That will give you a datastream. Need a scan tool.

I am also curious what the details are on the catalytic converter. Original, replaced, or otherwise?

Start with the basics to try and find out what you are missing, whether it'* fuel, air, or spark.

I wonder if it has a vacuum leak.

I had a similar problem of my 92 3.3 stalling completely under high rpm'* when warm.
Turns out it was the engine temp sending unit-sensor was bad, giving bad readings to the computer.
Replace the simple sensor and no more problem!

Hopefully 1Climbingwall will come back and let us know how it turned out.