Idle throttle switch:
Before replacing, I would try removing it and cleaning. It worked for me. Spray inside with carburetor cleaner while holding with open end down. Give it a few seconds to dry then a quick shot of WD-40 and reinstall.

High Idle: These cars use a lot of vacuum powered engine controls. High idle can often be isolated to a vacuum leak. Please check hoses and fittings carefully. There is one fitting often overlooked at the rear (firewall end) of the engine. It is hard to see and access but lives in an oil and heat rich environment thus is often the first to fail. Remove your air filter housing and look straight down behind the engine toward the passenger side while using a flashlight.

Something in common: Some years ago, I had the pleasure to liaison on a joint project with the Canadian Navy. I spent about five weeks underway on HMCS Annapolis, one of your helicopter frigates. We visited Nanaimo as well as San Diego. Had a great time. You Canadians know how to be uninhibited. I understand Annapolis is now retired.