My 84 celica GTS (259,000 miles, 4 cyl) had similar symptoms, cured by replacing the distributer
The distributer base and drive shaft/gear (?) had worn to the point of major slop when cold and things hadn't yet expanded. The excess play was allowing severe wear. It has been a year, and I am out of my element here, but that is more or less what I recall the tech saying. I went in there wanting it to be just a marginal coil or coil wire, but.......
2003 Firemist Red/grey leather SL 500
2015 Palladium Silver/black mbtex GLK 350
1987 Smoke Silver/burgundy mbtex 300E Sportline (SOLD)
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