D Max (classic) LBZ possible head gasket failure any gurus and they're professional opinion on the subject would be great before I give in head first ,no punt intended... Thanks in advance
I'd throw a block off plate in the egr first just to eliminate that from the equation. It'll throw an insufficient egr flow code, but it's probably the easiest way let you know if that's the problem.
Does the hose stay hard over a night of sitting? Is there any dark color in the degas bottle? If either of these I would say a hg. Last lbz I had same issue it was an hg. I could brake torque in 4x4 with no cap and push coolant out.