I can't offer any help here, Max.

I just wanted to say that my '85 is totally stock and I run regular
gasoline from the pump and I don't use any additives such as HEET.
During the winter I use Castrol Syntec 5W 50 oil and the engine starts,
idles and runs fine, even when cold, with outside temperatures colder
than minus 20� Fahrenheit.

I hope you can find and rectify your problem.

Mike
Houlton, Maine