I actually have a 1977 celica gt that I bought new from the dealer with the 20R engine. Ive heard of the problems your having, I actually rebuilt the celica at 100,000 miles and installed the EFI and turbocharger from a 1987 4Runner. Along with the 22R head the old 20R motor still runs strong with 295,000 miles. (It can also outrun V8 Mustangs if you ask it nice).