Have you checked for excessive play in the butterfly valve shaft ?.

DubTrub, can't argue with those numbers :ok: . My Cub was an L4 with a filter on the cold air but, as normal, no filter on the hot air.

Regarding the grass, I was thinking about clumps of cut grass rather than the odd bit.

PS We used Arizona red dust as it was available in a range of different, closely controlled, grain sizes. The fine stuff was good for polishing out scratches in sunglasses when mixed with a bit of water!