Catalytic Converter Overheating / Starting Problems

Someone please HELP!
After about an hour of driving on the highway my 89 Cherokee 4.0L started stalling for 5-10 sec and then started again on its own. It did this a few times and then I heard some thumping from underneath. I pulled over and found the Catalytic Converter glowing red hot. I let it cool off for 30 min and made it home driving slow. I had a new Cat installed and after an hour of driving on the highway it starting doing the same thing again.
Now another problem has popped up. Pulling out of a parking lot the car sputtered, dieseling, and misfired and would not restart. The engine would just crank over. I tried starting it a couple hours later and it started.
I have now idea what caused the Cat to overheat or the new problem of misfiring and not starting.

Check for spark,

In no spark or partial spark then it could be your CPS, Coil or cam position sensor (if you have one).

There are a few things that can cause a CAT to overheat. Misfires or overly Rich A/F mixture, because raw gas/unburnt hydro-carbons are burning in the CAT itself. OR excessive pollution of one or more types from the motor, usually caused by a serious malfuntion of the motor.

Clogging is also possible, but that seems unlikely, since the same happened with the brand new CAT, as well, CATS usually clog up from the factors I mentioned above.

Sounds like the root of the problem is something with your engine, most likely the engine control, and the CAT glowing is just one of the other symptoms.

Like mentioned, check out the ignition and any causes for misfires. As well, check everything, a bad EGR could even be a cause or contributor to this.

Can you check Fault Codes in an '89? Might as well try the Key On-Off-On-Off-On method to get the "CEL" to blink out codes. Most likely the codes will clue you into the problem with the motor that is causing the stalling and CAT overheating.

Hey y'all,

Thank you for y'alls comments and suggestions. I pulled out the CPS and there was a chip on the sensor magnet, a metal sliver about 1/64 X 1/4. I figure that was interupting the signal. I theorize that when the enging was stalling, the un-ignited fuel from the cylinders was getting pushed right into the CAT causing it to fail. Since I bought a new sensor before pulling the old one, I just put the new one in instead of cleaning off the old one. It ran normal for the two hour drive back home.

Wow, thats a story to tell the kids...a sliver of metal hung up in the CPS causing a cherry red hot Cat! Never would have guessed that one. Sounds like you got off real easy on that one! Time to:
arty:

Hey ya'll,
Guess what? Yup, I stalled out on the highway again and then o'l Betsy wouldn't start up at all after running fine for a week. She would crank over with no spark. I changed out the ICM/coil and she's good to go again.