I'm thinking the Cranes' are the problem just not sure how. I would recheck their slip fit on the shafts cold and when hot/noisy shut it down & undo the adjusters/take out the pushrods & see if any of them are binding(reciprocating and side to side). You'd need to work fast to get em while they are hot which may take several efforts as it may only be one or several that are binding so all would need to be checked while hot. I'm doing alot of guessing here. This is a tough one. Plus there's the (related) idle speedup issue