security of a block cipher mode of operation
No, this mode as listed does not provide integrity of the decrypted plaintext.

An active attacker can flip arbitrary bits from the first 64 bits of the decrypted plaintext freely without causing a decryption failure.  He can do this by modifying the $iv$; the decrypted $tag_0$ will authenticate (because the $iv$ is not used to compute that), and then the decryption process will apply the modified $iv$ to the decrypted $plaintext_0$