Hi Scotty its me again with my 3S-GE 94 Celica.
I bothered you couple times in the past with essays about my weird problem with the car. You suggested distributor assembly, which made the car run much, much better, but still had issue with random stalling and random limp mode. Car was running fine and at random was going into limp mode and retarded timing by 5 degrees (i think knock sensor retarded the timing). In the last one you suggested fuel pressure. It turns out my fuel pump was weak. Replaced it with brand new and car runs like new!
What i think was happening:
a) Weak fuel pump was causing spark plugs to foul, which randomly caused very weak spark or sometimes none at all. That triggered knock which put car into limp mode.
b) Weak fuel pump was causing car to run lean which caused random premature detonations and triggered knock sensor.
Does it make any sense? Anyway, it is all good now!
Took me a while to fix it since your suggestion about fuel pressure but its freezing in UK!
It is quite amazing that the car was checked out by 5!! different mechanics and none of them was able to analyze the car properly, while you diagnosed it perfectly just from a wall of my text and one video.
I just wanted to thank you so much for your time, you saved my baby! All the best Scotty!
P.S -- Oops! Sorry for another wall of text!