Hello,
It's probably good timing that I changed the ECT sensor in the 1991 because my 1990 (the daily driver) starts fine when cold, but gives me some difficulty starting if the engine is hot. I may replace the ECT sensor for the 1990 in the near future because this is a similar issue that my 1991 had back when it was my regular car (and I suspected the problems were related).
The 1991 is not street legal (I just run it in the driveway), so I set the temp low (I can change it on a whim) so that I can test the wiring and thermostat I bought. When it's roadworthy, I will change it to be closer to the fan speed strategy you provided.
I totally forgot to get a combustion test kit. That's officially my new priority now. I will check the other symptoms you mentioned as well.
A part of me is upset that my headgaskets could have blown, but I've also owned this supercoupe since November 2012 and my other one since May 2015 and I haven't had to face this issue yet. I've been waiting for the "axe to drop" for years now. If it turns out my gaskets need replacing, I will be strangely relieved because if I take really good care of the new head gaskets, they should outlast the car. I will pamper these gaskets and never let the car overheat ever again. I also had a mechanic tell me that replacing the ECT sensor WITHOUT burping the system afterwards could have resulted in a tiny airbubble getting caught in the engine and blowing the gasket. I think my gaskets could have been on their last-leg anyways, but I'll definitely "burp" the system whenever I change the ECT sensor or Temp sending unit on the 1990.
Thanks for your help![]()