Was Jacob a true believer when Isaac sent him to Paddan Aram?

No, Jacob was not a true believer at that time. Even in his unbelief, he was still under the auspices of faith, but he was not a true believer. He obeyed his father, but that obedience did not make him a true believer.

Les explains that Jacob was still Jacob, and although he obeyed his father Isaac by going to Paddan Aram to Laban, the son of Bethuel the Syrian, and avoided marrying a Canaanite woman, his obedience did not make him a true believer. Les teaches that even in his unbelief, Jacob was under the auspices of faith, but he was not yet a true believer. Esau saw that Jacob obeyed his father and had gone, but Jacob's spiritual state remained one of unbelief at that point.

Genesis 28:5

And Isaac sent away Jacob: and he went to Padanaram unto Laban, son of Bethuel the Syrian, the brother of Rebekah, Jacob’s and Esau’s mother.

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Was Jacob a believer when he left for a far country?

No. When Jacob went up into the far country, he was still an unbeliever, still the supplanter and the deceiver. Though he was under the Almighty God’s protection and blessing, that did not make him a believer; his own heart remained unbelieving at that time.