I have seen where a bad harmonic balance caused a issue with the crankshaft position sensor but that was a older 3800 with the groves in the sensor, Seems you tried or tested about everything that's related I wish you luck.

 

Yup ...Replaced the ICM . Still have same crap cylinder #3 misfire

 

No one else had this problem?? ....And resolved it? Im giving up, gonna have take her to a shop i guess

 

I had the same problem. Mine was a bad plug wire. I am not saying this is your problem too but I could not correct my problem until I ohm'd the wires. I ordered new ones and it corrected my issue. I hope you figure this out.

 

Is the CEL actually flashing? Did you clear the codes and have it pop back up? Check the ground wire connection under the ICM bracket too.

 

Plug wires allteady replaced- supercharged...Yes -nitehawk its flashing , cleared and came back many times. Ground is good. Actually bought a Crank position sensor today .... Gonna try one more time .

 

I did read that you replaced the wires but I would still ohm them for proper spark if you can. Good luck with the crank position sensor.

 

Let's start with, what are all the trouble codes the car is throwing.... A LOT of money has been thrown around in parts in this rig, if we have all the codes the computer is throwing (and I mean the P numbers, not what a scan tool says it translates to), we might be able to scrape us some better info.

I know you said you replaced the ICM so my next blurb is pointless, but I'll share anyways. Those ICM tests at the parts store are limited. There is no heavy load on the ICM. I just went through this on my mom's car (3800 powered LeSabre). She had a horrible mis-fire on two cylinders shared by a coil. Long story short, ruled out the coil. Then had the parts store tested the ICM multiple times, it passed. Later that day I believe I should have had them modify their test. They connected at the main connector, used an alligator clip lead the first blade for the first coil and then an alegator clip lead on the second blade for all coils. I should have had them move that one clip lead to each coil position. Oh well, know for next time.
Using a inline test light (goes between the plug and the wire or the coil and the wire). Found very weak spark with it. Changed the ICM problem solved.

 

Dont know how this could possibly help ... Its throwing code P0303 which is (cylinder#3misfire) . Havent changed my crank sensor yet. Gonna get the seal while i have the pulley off

 

I know it's probably been covered, but have you changed the spark plugs and ensured the misfiring one is gapped correctly?