Why Doctor Who beats Back To The Future

If Doc Brown had gone back to 1885 and sent Marty a letter in 1955, and Mmarty had shown it to the young Doc Brown in 1955, then the old Doc Brown from 1985 that is living in 1885 would have remembered having sent Marty that letter and known that he got it, and if he had known that he got it, he could have then changed his choices so as to not be sitting in the stupid DeLorean when it got struck by lightning, or at least would have parked it, which would have allowed him to change the past and the present and the future at the same time.

As it is the doctor from 1885 is shocked that Marty shows up, when in reality he should remember Marty having received the letter in 1955 when Doc Brown was 30 years younger. He remembers to wear a silly bullet proof vest against the Libyans, why not that?

Of course, when the fuel line got hit they could have just siphoned the rest of the gas off the DeLorean that Doc Brown had shoved in a cave, and then he could have written a note that said "You'll need a new fuel line and some more gas, sorry". 

But if I'm going there, then a half-dozen intergrated circuits that look like microcontrollers *could not* be replaced by a dozen vacuum tubes and some weird wires.

Also, if they had left the almanac in 1955 and Biff got rich, then as soon as they zapped into the future they both would have ceased to exist. His girlfriend Jennifer had "the world shift around her and she woke up in the morning in normal 1985 as if nothing had happened". What???

See in Doctor Who's land he would have known he was going to send himself the letter and done it anyway and all these things would suddenly fall into place and they'd have to get the girlfriend and take her in the time machine back to the real timeline or she would probably be in serious timey-wimey trouble.

Yes, these are the things I think about when waiting for a computer thing to finish.