Hi, if you see my post on the forum I mention a screw that popped out of the inlet in front of the carb. Check this, it seems oh too familiar .
Indecently, it happened again , I had a new one with new o ring to install and it saved the day.
The O ring can flatten and deteriorate and with the force from the intake manifold can pop out.
https://www.volvoforums.org.uk/showt...=322090&page=4