I have a e36 328ic (m52). I always run 93 octane.
It runs great, always has, but since I filled up at a less-than-quality gas station (I wasn't thinking clearly at the time!)--"South of the Border" at the nc/sc border, she hasn't idled well.
I tried refilling her with 93 from shell and putting in a whole bottle of stp fuel injector cleaner and a whole bottle of stp gas treatment, which stopped the problem, however I got down around a half-tank tonight and when I pulled into my apartment she started doing it again. Is there a way to clean all the crap out of my gas tank, without physically removing my gas tank? Please help me...