Cylinder 5 & 8 misfires - ideas?

Hi. I cannot figure out why I keep having misfires on cylinders 5 & 8. Maybe you all have some ideas? I think I’ve done all of the typical fixes: new injectors, coils, plugs, connectors, on and on and on. Pretty much everything and it still keeps showing up.

I only get misfires after car is fully warm. STFT does seem to be jumping up and down sometimes between -10 and 10 on both banks. Smoke tested and repaired all vacuum leaks I know of. Car seems to run perfectly smooth. The next thing I’m going to do is a compression test, which I admittedly, have been avoiding because I’m nervous about what I may find. The only thing I’ve noticed is that sometimes when I go to start the car, the brake pedal is hard to press so I assume there must be a small vacuum leak in the brake booster system somewhere?

Does anyone have any ideas or maybe has had the same experiences? I’m wondering about ECU drivers?

Thank you!

Okay, did a warm compression test. All cylinders were right at 190 +/- 5 psi. Thank goodness! :sweat_smile: I think that mechanically it’s very strong. But, that still doesn’t tell me what’s wrong. I’m thinking it’s electrical, since nearly all my other issues have been electrical.
The misfires are only cylinders 5 & 8 and only happen when car is warm (100c) and typically around 1400 rpm. Voltage was good.