Did you ever finish troubleshooting the coolant temp sensor (CTS) at various other temps? From your initial test some time ago, you already know that it's giving a bad reading at 80C. If I were you, I would complete this test first, before moving on to other things. The CTS is an easy, low cost fix, and definitely affects driveability issues. Doing a systematic diagnosis of the ignition and KE systems following the FSM troubleshooting procedures, is not difficult, and it'll point you in a better direction for a fix than jumping around, and in a lot less time.
