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Could it the battery, it has **** itselfAll jokes asside,
I am tipping the type of fuel you are using,
and an exhaust leak at the manifolds,
That model [inc VX & VY] had a tendency for the exhaust manifold studs/bolts to snap, and exhaust gasses to leak past the gaskets.
I had a similar issue,
I replaced the exhaust manifold gaskets, and the exhaust manifold studs/bolts on my L67.
or
Maybe the EGR valve is jammed or blocked ?
another member maybe able clarify if this can cause it.