Join the "Brick Wall" Club. I have found no Isaac in my family yet. Since it isn't a common name in the CARROLLs, it should be easier than "John" to find. When you can find the same name anywhere, you can sometimes find others in the family with that name.
Carroll is considered by most to be an Irish name. Is Isaac a common Irish name? Have you tried other spellings of the last name?
In the 1665/1666 will of Teage Corroll in Lancaster County, VA there was listed a son, Isake, b. 4 May, 1664. Same county 1755, will of Isaac Currell lists sons Jacob Currell and James Currell. There are marriages for Isaac Currells in 1772, 1815, and 1830.
If I were you I would definitely look at the records of Lancaster County, VA. Does the name Isake Corroll/Currell sound more German than Irish? Just a thought.