Charcoal injestion

[Pmac]

I posted this request for help recently but likely in the incorrect spot - it is not mouse droppings - the charcoal in all a uniform size and there is at least a cup(!)
"I found at least a cup of very small charcoal cylinder shaped (1/16th by 1/8th)pellets on top of my secondary air doors and in the bottom of the air cleaner two days ago. I put the pedal down on a country road and instead of the hearing the QJet moan – the engine was choking for air; I removed the lid and was shocked to find a cup (or more) of tiny black cylinders inside of the air filters , I swept them out as best I could and drove the ten miles home( no choice, rural area) the engine was barely running. I reckon something let go in the damned charcoal canister and when the air doors opened up it sucked the charcoal up the ‘clean air tube “ACLNR” ‘. The QJet is knackered, I know – but what about the engine? Has anyone seen this before? 1981 GMC C 1500 Canadian 305/350 camper spec. One more observation - the vacuum valve that closes the snorkel failed and although up to operating temperature the engine only had air coming in through the heat stove pipe ( and the clean air tube)."