Join Date: Aug 2007
Location: Sligo, Ireland.
Thinking about what happened with the oil breather 2 weeks ago, your intake manifold would have been already coated in sticky carbon gunk from the egr/age/dodgy thermostat/intake boot/maf, this will have picked up lots of that oil, and whatever air paths were there, into the cylinders, will have been greatly constricted with the extra gunk. That may burn off in time, hence your slight improvements in fuel use each time you run her. Or it may need one of those treatments which are pumped directly into the manifold. Worse case scenario, manifold off and cleaned by hand. Cat is a possibility, you can have the pipe removed, opened up, cat comb removed, weld up pipe and refitted.