Same issue last week. Replaced stock coil and ICM. Nope. Changed optispark now fixed. My opti was an acdelco unit I payed nearly $450 dollars for and it lasted almost 10 thousand miles. Went with a all new unit from O'relleys for $200. Life time warranty no questions asked. If it doesn't last so what, get a new one for free. No more Dephi or Delco overpriced opti for me with no warranty.

 

Thanks for the response!

Your Ac Delco Opti only lasted 10k? I had a chinese p.o.s. last 20k. Dissected it and the worst part was the cap and rotor, both were toast! The reluctor wheel had some oil on it as well. Just got my new Delphi unit for $400 and new Bosch water pump. At the moment I'm trying to get this water pump drive seal installed with the Sharpie cap! Kind of a pain, but I think i'll get it on the second try. The first seal folded over and looked as though I obstructed it in the process.

 

I just wanted to update. Opti was the issue! Car has been reliable as ever! Still working the air out of the cooling system, other than that, no complaints!