So after reading and reading and reading, systematically addressing anything I could think of and replacing countless parts I'm no further ahead. P0015 cam bank 1 over retarded

Basic background,
2007 mini s ~70k auto
Car was in a minor front end accident (purchased this way)
Chain blew well in the shop.
Mechanic replaced chain, guide, tensioner, ect. Head was removed and inspected by a machine shop.
Tranny blew (still in the shop, verified bad) replaced

Car came to me with various cel codes for engine timing, thermostat, various sensors... Had access to two identical cars, one parts and one good running. Sorted through every issue except p0015 bank 1 cam over retarded.
1. Replaced the cam sensor (top of valve cover)
2. Checked all connections
3. Checked timing as per mini specs with mini tool
4. Swapped the vanos solenoid (back left of head)
5. Swapped vanos and retimed
6. Rechecked timing

Might be something I'm have forgotten but needless to say I'm out of ideas here. I'm not a mini specialist but I've used the shop manual and rechecked everything so what am I missing? The car starts fine idles a touch high until warm an then it's fine. After a while it will surge a tad and even stall intermittently. If I clear the code car runs great for 30 miles or so symptoms resume and code returns.

Thanks in advance. Dan

 

in what order do you attach the cam gears/ crank sprocket / timing chain tensioner? do you hold the exhaust cam sprocket in place while you tighten it? did you replace the cam and crank bolts during service? is there any slack in the chain in front of the intake cam? have you done a compression or leak down test?

 

Any resolve on this issue? I am having same trouble with 2008 n12 cooper.