Re: 1968 Mercury 3.9 stalling at idle Home › Forum › Ask A Member › 1968 Mercury 3.9 stalling at idle › Re: 1968 Mercury 3.9 stalling at idle daveskoReplies: 94Topics: 34 August 2, 2018 at 9:50 pm #80570 Pretty sure I have it fixed now. Had initial setting at 1 1/2 took it to 1 turn out and she idled fine for 1/2hr. Adjusted to 3/4 out final setting as per leeroys ramblings.