We were greeted by another beautiful sunny day which made for pleasant driving.
Unfortunately a small noise we noticed in the vehicle yesterday was a little more insistent today so at Boise we were lucky enough to find a Ford dealer open and spent an hour there while a mechanic took the ER for a test drive. His diagnosis - You have an exhaust leak, it will be annoying but won't damage anything. If it gets really bad you will loose turbo boost and hence power.
Not what we wanted to hear - but we continued.
We stopped for the night at Three Island Crossing State Park. This is the site at which most settlers on the Oregon trail crossed the Snake River. Apparently the settlers crossed here on their way to Fort Boise as the country after the crossing had better water and feed for animals than the alternative route.
We spent the evening in warm weather exploring the park and its surroundings. It was a very pleasant place.