2 things I just thought of.

Have you checked the fuel mixture/lambda?

After engine is upto temp shut it down and let it sit for 2-3mins. Press down the air flow sensor and smell inside the fuel distributor. If there is a very strong fuel smell the the fuel distributor might be leaking directly into the manifold through the fuel distributor plunger..........just a thought

__________________
Alex.

MB Tech
Sydney, Australia
Volvo 122S
W201 190D 2.5 manual
W202 C240
W203 C32