1997 Buick Riviera starting/stalling problem

HI Everyone,
I have a 1997 Buick Riviera with the supercharged 3.8 engine in it. I'm having one heck of a problem. The car has been to
my local mechanic and two buick dealers and they can't figure it out. I'm close to just starting to replace parts. Here's some symtoms:
1. If I drive the car to operating temp (200) and let the car sit for a bit (like if I go out to eat) if the car temp drops down between the 6th and 7th tick on the temp guage (which appears to be 160 degrees) it will crank but not start. This doesnt happen all the time, maybe 1 or 2 out of ten times.
2. When I am at a red light the car may stall or attempt to stall but catch itself. Again this is not all the time so it's hard to reproduce.
3. When I am driving if I hit the gas hard the car will sometimes stall. Doesn't happen all the time. Appears to happen when the car downshifts. I have reporduced it twice, two days in a row to where if the car is between the 6th and 7th tick on the temp guage and I floor it it stalls out. It takes about 10 minutes of cranking to get it started. It does sound like it fires one or two cylinders every once and a while
4. Sometimes I'll be coasting down a hill, not hitting the gas and it'll just turn off.
5. It's throwing a crank shaft position sensor problem code.
I've changed the sparkplugs and wires and the ignition coil. The crank shaft posisiton sensor was checked by all three places and they say it's ok. Wiring harnesses were checked. My local mechanic had the car for about 5 months total time and can't figure it out.
So the key points here is that these problems occur 90% of the time when the car is between the 6th and 7th tick on the temp guage. Once it cools down to the 5th tick it starts fine. When I turn the key to unlock I can hear the fuel pump prime.
Any ideas?
Sam
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More info. I have been able to sucessfully stall the engine 3 times now by starting at cold engine and flooring it as soon as it hits the 7th tick mark on the temp guage. It doesnt do it at the 6 tick or the 8th tick.
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First of all you cannot check the cps when the problem is not there it will show good, If possible try to get a scanner on it when it won't start and see if you have cranking rpms, if not suspect ICM or cps, or the wiring from the cps to the icm. You could also check for spark and /or injector pulse during the no start event, these are basic diagnostic steps.

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It's a little rough to check stuff like this when you are on the side of the road with cars driving around you. =(
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True, but at some point ,somehow if you are going top fix this without professional help, that is what has to be done.

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New info. The car wouldnt start this morning. It rained heavilylast night. The car would crank fine, it just wouldnt catch. I pulled the sparkplug out and could smell gas. I put the plug end on the engine block and it wasn't firing. After about 30 seconds of cranking the plug started firing and the car started up (ran rough, obviously it don't have one of its plugs in it.) Any thoughts?
My suspects are computer or the crank shaft position sensor. I am getting P0336 code. Does anyone know if the crankshaft position sensor is giving a problem does the computer still fire the injectors?
Thanks,
Sam
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