I had this problem on my old rb20det. First thing in the morning itd miss and overfuel cronic, around 1/4 throttle it be like a rev limiter poping and backfiring like crazy, full throttle was fine, itd rev out without an issue but 1/4 was f**ked. It wouldnt idle proplerly then magically itd fix itself and be fine after about 10mins. Some days itd be fine as well for no good reason. Replaced fuel filters, ran injector cleaner, cleaned out the AAC and the throttle body to no avail, it did make it run smoother when warm though. I think it was just massively overfueling though as you could almost see a cloud of black smoke when it was happening, itd make your eyes sting and you would feel dizzy sitting at the lights.
I changed plugs, coils all spark related stuff but it didnt fix the problem in the slightest, replaced O2 sensor and a few other things. Never solved it and ended up selling the car for other reasons. A few people suggested temp sensor and that the ECU could have just been buggered.