I had a similar high idle problem on cold mornings. To me in Texas that is below 60.
Problem turned out to be the cruise control linkage rod to the mechanical control box lower right of injection pump. High idle would go away when engine warmed or if I raised the hood and pushed the top linkages back to normal idle. I tried spray lube on linkages and cables to now avail.

Linkage rod from cruise control to injection pump throttle causing high rpm til warm

Only time my idle was ' lumpy ' if that means a little shaky was after new motor mounts. That went away after a couple of months. Don't understand why but hasn't been a problem since.