Oh dear! Trouble for Mcflys please continue soon.

Owie! When did Marty learn how to cartwheel?

Entertaining story. It looks like we've go the missing Tannen here, even though he's only 20 years younger than Biff. He's just as bad as his father, that's for sure. I wish they could've gotten away with their adventure. Also, I can't help but thinking that Lorraine seems more like she'd be in the original timeline.

Just one thing: In the future (no pun intended) I'd suggest putting more paragraph breaks in, especially at the quotes. It's easy to get lost in the big chunk of words.