I have been told that John Wesley read the pre-Schism fathers a lot, and was influenced by them.
Is this so, and if so, to what extent and how was his doctrine influenced by them?
Interesting question. Wesley, as an Anglican, would have learned to understand Scripture through the lenses of Tradition and Reason. Tradition for him would have included everything from his contemporary Pietists back to the early church fathers.
I did a quick search and discovered that Wesley believed those closest to the beginning of the church had an advantage over modern Christians:
Wesley's teaching on Christian Perfection was partly influenced by his reading of the fathers, and his doctrine of Prevenient Grace appears to have been derived from Chrysostom; beyond that, I'm not sure how much he drew from the ancient fathers. The primary influences on his theology would have been his contemporary Pietists as well as the writings of Jacobus Arminius.