Can an executor start selling off items of an estate that were willed to an heir?

The executor has to pay all debts before dispersing any ets. If the only ets are non liquid, he may have to sell some to settle the debts. If you specifically want the ets as is (not just the remaining cash value), you could approach the executor and offer to loan the estate the funds to settle the debts, which would allow him to p the ets to you intact. That may be preferable to a quick sale of the house, which invariably will net a lower value.