I was seriously going to sell my car, but i want to keep it, i dont want to be a

and go the easier way out. I want to fix and save this poor 5.0, if i do i bet it will feel awesome. Knowing i did it all myself, plus i think my car is in pretty good condition than anything else i would find around here, 5.0s are a rarity in oklahoma.... at least up where i am.
The only things i can think of that are making my car slow, is
133k mile motor, slightly worn i would say
bad balancer( not 100% sure on this but motor does shake, and shows some other signs)
some unknow slap from my number 5 cyl, cany hear it often but its there, this is where my knock came from when i was racing.
and
stretched shift cable, unable to hold 1st, so i am cursed with a shift at 4500 ( shift cable should be in monday)

))