Was experiencing shuddering feeling at anything other than full throttle.

Was also using to much methanol. Found the fluid was flowing at a rate well in excess of the injection pulse settings.
Installed a check valve to correct the excess flow.

Nitrous has been firing at only 1/4 throttle. Reset the controller as it had somehow lost the settings.

Cleaned the MAF.

All is well.

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X5 4.6 2002 Black Sap, Black interior. 2013 X5M Melbourne Red, Bamboo interior
Dallas