If it'* still causing problems when hot, then you haven't found the bad coil. I've seen several work fine cold, then fail hot. And that'* what it sounds like is happening with you. Did you say you changed one coil already? If so, use that coil you took off and swap a different coil and see if it corrects the problem.
Because you have now determined you don't have spark you can forget everything else and concentrate on the ignition system. Your options are, bad coil, bad ICM, there are other things but they tend to be all the time, not just when hot.
May not be a bad idea to remove all the coils, lift up the ICM, and clean everything up. A little corrosion can cause a lot of problems.
SAVING THE WORLD ONE BONNEVILLE AT A TIME
1997,1998,2000,2005 year confused Bonneville SSExi. Stock? ish.
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