i just replaced the opti spark on my 96 Z28 with a remanufactured one from advance auto parts. it started up just fine at the hit of the key when it was cold. i started it a few more times and let it warm up a little to bleed of the air out of the cooling system then it started kinda hard again like before. i took it down the road about a mile at 30 mph, turned it off and tried to hit it again and it wouldn't start at all even with the gas all the way to the floor. could the opti spark i just put on there have gone out that fast? or could it be somthing else? i was hagving alot of the symptoms of a bad opti when it was getting up to temp sitting in the drive way at idle. rough idle, missing a bit when i drove it, then like i said just wouldn't start when it was hot. any help would be awesome. right now i don't have any codes to throw out to you guys cause i don't have a reader, but i'll get it to some place that does as soon as i can and i'll post the codes when i have them.

 

I had a similar problem with my 94 z28. The car ran great until the bearing in the distributor went bad. So i changed the opti and it fired up great cold but the hotter it got the weaker the spark would be. I changed the ignition coil and that fixed it after finding a load of broken wires and bad connectors.Check the twoelectricalconnectors going into the coil. The wires right where theygo into theplug have a tendancy to break and hang on by 1 or 2 threads with the insulation semi intact. I found all kinds of wire problems... i had to replace both of theconnectors going into the coil, the control module plug. Ichanged the ground strap that goes from the coil/control module assembly to the driver side fender well.I had to get a new 4 wire weatherpack connectorfor the main harness to the distributor because the pins inside werent making good connection evenafter i tried retensioning them if i wiggled the plug the car would die.and i just found that a wire isbroken near my mass air flow plug but i was able to temp. fix that with a connector.
The thing is the car is old and when you go pulling electrical connectors and moving wires around they are brittle from years of engine temps of 200+ degrees and wires break easy. just look everything over really good and you will fix it. I took me about a month of banging my head against the wall but i finally figured it out, just a coil (msd coil maybe less than 1yr old, didnt suspect it)and i found a bunch of wires that would have gave me a lot of problems in the near future.