Hey mate, i dont have a rb26 but i had the same problem with my rb20. I replaced as many things as i could. I cleaned all these parts people are telling you to clean, but after everything i finally found after trying a 3rd afm - it finally went away! Another mate had the same problem and we tried my afm on his car and it made no difference so we tried my crank agle sensor on his car and it fixed it. So basically it is a process of trial and error! But try a few different air flow meters. Hope that helps!