I did answer the question. He needs to run slower than his 2.0 mmol level.
Is 8 minutes a mile below his 2.0 level. I don't know?
Which is why I suggest getting the HRM, doing a max test and start by running at 70% of max. My guess is the OP does do some running at slower than 2.0 but he offsets it by running way too many of his runs OVER.
With the strength of his Anaerobic system, running 6:30 pace is a piece of cake yet it is TOO fast for him (probably 3.0 mmol). Chances are he's powering that pace with his Anaerobic system (and glycogen) and because he never runs a full marathon in training he is surprised to learn that he cannot hold 6:30 pace without running out of fuel.
Here's another Hadd quote:
"To me, the prime requirement for marathon success is (what we might term) "comfort" at race pace.
If your lactate at M-pace is too high, which makes you uneconomical (as regards to fuel), you will crash. How early and how hard you crash depends on how bad your lactate is at M-pace.
Train so that M-lactate is low enough and you will not crash (assuming you carbo load properly).
It has nothing to do with how many miles you have run, or how long your long run has been, but how "comfortable" (in lactate/economy terms) you are at M-pace. Fix that and you're made in the shade."