I have a 2003 FSI Polo and on idle its lumpy, its worse when I use a higher octaine unleaded fuel. I've always used Shell unleaded as my day to day car is a high performance Japanese import (always had a vw for a toy
). It wasn't until I was caught short and dived into a small garage to fill up and the idle after a few miles was considerably less lumpy. Its not that lumpy that it fails but its just annoying. I always thought that higher octaine fuel help correct lumpy idle not hinder it?I was wondering if anyone had any ideas before I put it in the garage