Well, heres the deal:
-starts fine when cold
-shuts off and dies
-wont start after being run
-ROUGH idle
-black smoke from exhaust
-Im sure there is more that I will add

Havent had a chance to get the code read, might do that tm if it starts.
My Dad suggested that it was the crack shaft position sensor. We replaced that... no luck. Same problem.

I think it might be a clogged cat. It may have a little water left in it from my accident. Any ideas? my next step would be to replace the cat.

Oooh, a challenge! Yessir, I accept.

I assume your SSEi is the 3800 Series-II Supercharged? I have a naturally-aspirated 3800 Series-II, I think I might be able to help.

First and foremost, your dad was on the right track. Crankshaft Position Sensors can be heat-sensitive, and are a common fail point on the 3800.

For future reference, a hint & tip to file away in the gray matter... One thing you can try when it gets hot and craps out, is to spray the CPS with computer keyboard cleaner. The propellant in the can is compressed and becomes cold when sprayed; with any luck this will "freeze" the sensor and if it is a heat-related failure on the CPS, this will most likely identify it.

Being that you have already replaced that, let'* move on...

Another thing to try is the MAF (Mass Airflow Sensor). This will cause the hard/no restart problem, the rough idle, and stalling when the car reaches Closed Loop mode. To begin, I would disconnect the MAF with the ignition off; start it and see if the conditions improve. If so, the first thing you can try is to use ONLY MASS AIRFLOW SENSOR CLEANER to clean the sensor. Let it air dry completely. If you have a strong magnifying glass you can peek and see if the tiny wire coils are broken.

You will need to purchase or borrow what are called "Tamper Resistant Torx" bits to remove the sensor. I personally have had 6 of these sensors go, the original one died and then I spent the next 4 or 5 weeks replacing 4 of them. Do *NOT* buy a BWD brand sensor if this turns out to be the problem. Spend a few bucks more and get a better brand, if it is indeed bad. (This is where buying the tamper-proof Torx bits turned out to be a bonus, I could swap defective units in the parking lot of the Cheap @$$ Parts House.)

Also, another thing that is possible is the Cam Sensor. Never personally had to deal with them on the 3800, but the same symptoms existed on my friend'* '05 Stratus, and replacing the cam sensor had her back on the road in less than half an hour.

A clogged cat is a possibility, one thing you might want to check is to *gently* tap the side of the cat with a rubber mallet and see if you hear the honeycombs or metal debris rattling around inside. If you do, that'* a pretty good sign of a clogged cat. Also, most exhaust shops can do a backpressure test.

Additionally, you can unscrew the O2 sensor and see if that makes it run better. Just do so VERY sparingly, as hot exhaust gases are pumping out into the engine compartment and may cause fire or other damage. Try it only as a diagnosis, and then reinstall it.

And, if you have the Supercharged 3800, I would pull the 'charger belt and see if the 'charger pulley spins freely, just as a "while-I'm-here." Not sure how to test the supercharger otherwise, but a friend'* wife'* '07 Riviera 3800 Supercharged had the 'charger go, and it had similar driveability issues.

Good luck!

Oh! And check/clean the electronic EGR valve. Just occurred to me as I clicked "Post." LOL And of course check all connections and vacuum/emissions lines.

MAF is a possibility, and easy to check, but I would lean more to the EGR sticking.

Pull the MAF and see if the idle clears up. While you have it off, clean it with a MAF cleaner. You will see a small sensor element that is probably black on a fine wire. Spray until shiney. Do not use anything other than MAF cleaner.

Tap on the EGR when it is idling rough to see if it clears up. Pull the EGR and check for carbon deposits, clean as required.

Check fuel pressure.

Is the CEL lit? Is it flashing? Scan for diagnostic trouble codes.

the carnk sensor or its wires/connector. the wires can cause the same no start issue. so can the ICM.

Well I got my car back from the shop. They cleaned up the MAF and so far its running fine. I wish I had more time with it because I could have probly just cleaned it myself. If thats all that was wrong with it...

The thermistors get a bit dirty after a while, which is why it is good to get some MAF cleaner, and every time you service the air filter, clean the MAF.
My MAF went bad in two ways, the tip came off and would spin inside the TB, so the car would not start on occasion, and when it did occasionally it got really sluggish.
After I removed the tip it ran better, but I still got an occasional misfire in cylinder #3, as the MAF readings were just a tad off, I'd have to find my old pics to say just how much off it was, I know it was not enough that you'd think it would cause a problem, yet at idle it really showed how much being off a tad mattered.
It only takes a couple of minutes to remove and clean, just try not to mess with the tip, if you find the plastic tip comes off way too easily, my advice would be to remove the tip altogether, until you can replace it with one that the tip is still tightly on, I took readings with, and without the tip, there was no real change that I could see.

Just an update on this. I Just got the bill from the shop. $300 to replace the MAF. I wish i would have tried to clean it first haha.

$300??!!?!? Are you kidding me? Its like 150 for the part itself and its 2 screws!!!! My 7 year old daughter could have changed that out for a lolly pop!!

I know its ridiculous! Could have bought a scanner got the part and installed it myself. save like 100 bucks...