I haven't really kept up with American Dad since maybe the second season, but it has quite a cult following. Enough to get it uncancelled over at TBS, and friends of mine constantly tell me I should check it out and that it's much more tolerable than Family Guy.
I might have to check out this most recent episode which features the voice of James Hetfield, playing water polo coach James Hetfield (although not the same James Hetfield as Metallica even though they look the same and have the same tattoos and he has all the guitars). That seems to be the goof. Our buddy Zach Shaw caught the episode and posted a few clips on his Instagram, which include some bits of "Master of Puppets." Here's two clips:
You can watch the full episode on TBS's website.