Are your O2 sensors recent?92 3FE owner here too, center locked etc.
I desmogged mine as soon as I could (EGR, AI & Pump, & Cats) and with lots of trips to the garage for work out of my comfort zone, and lots of work that is in my comfort zone, I'm blown away by how well it runs compared to when I first got it. (Fixing the exhaust leaks made the biggest difference).
Frustrating thing is, I'm still getting super low MPG compared to "posted" averages. 8mpg with city driving only and 12 with highway. I know that most are getting low averages, but my exhaust has such a noticeable fuel smell that I'm sure there is an inefficiency somewhere in there. Is an injector overhaul or valve adjustment going to make any real difference here?