85 hp 4 cyl problems

[Jollymon]

I have several questions about my 85 hp. I purchased this motor after seeing it run on a muff, all seemed fine. After getting it home and starting
to clean it up, I realized that the wiring was shot. It looked good but was corroded internally. I have replaced the internal wiring harness, stator, trigger, and rectifier. The motor started right up to my surprize and joy. But after a couple of minutes on the muff I turned off the key, it didn't stop. I had to choke it manually to stop the motor. I verified my wiring with two different diagrams. The wiring harness had an extra lead that is not shown on either diagram, it is a violet color. Any thoughts as to where it is supposed to go? The choke will not activate from the switch, I plan to test it to make sure it is good. What is the purpose of the mercury switch?
But the major problem is the motor won't shut off with the key. Any suggestions will be appreciated.

[Jollymon]

After a careful look today I solved a couple of problems. I verified that I had a good ground for the lead in the wiring harness. Choke now works and the motor shuts off with the key. The lead I thought was violet was a odd shade of brown and I made it down on the rectifier. Make sure you have very good light when figuring out wire colors.

The motor now starts and stops as it should. However, it has a fast idle and surges at speed. Any tips on set up and adjustments?