i have codes that are all dealing with misfiring on 1-3-5. i did a tuneup on it. i light goes out, i drive it for a couple of days the light comes back on reading misfiring on a different cylinder. it is always on that side of the cylinders. It came on again today it reads misfiring on cylinder 3. I have done tuneup after tuneup, change sensors, changed fuel injectors, can any one please help me.