I am loathe to take it to a dealer. As above they are parts replacers.

Everyone thinks BMW dealers are the pinnacle of technical expertise, with fastidious old german mechanics in the back, with a team of software wizkids to support.... FAR from true.

While you CAN find expertise, it is rare. All they do is run tests, start replacing parts the computer says might be bad.

Also the concept of the 'magic bullet' fix seems to plague owners...by this I mean "do all the diagnostics, and tell me the single 'nut' 'part' or 'sensor' that is bad to fix all these symptoms. Sometimes you can, sometimes you cant.

Your car may have been opened- THAT creates an impossible diagnostic scenario- a dealer assumes 'as factory' condition. Add a 'someone messed with the timing' and they can have you cha$$ing your tail.

This is why you do not buy cars with CELs thinking "oh its an easy fix"...especially from dealerships since THEY have mechanics and those mechanics can (and will) do the easy fixes!