Starting problems

Ok guys i have a 1988 b2000 one day i went to start it and it was cranking really slow like a dead battery so i put a new battery in and the starter looked rough so i put a new one in as well and it still dose it. Also after it warms up it will hardly crank at all but it has a fully charged battery and a good stater that has been tested what the heck could it be now i did notice that behind my speedo cluster there was a brown wire the was fried to i spliced in and fixed that and the only other thing i have done is that my ignition switch broke (the whit part with the slot in it) and i went down to the junk yard to get a new one and they didn't have a b so i got one out of a 626 and it was the same plugs so i put it in. Any help would be great i am really getting tired of pop starting it.

bad cable or ground from the battery?

yeah thats what i thought but the cable is only 10-12" long goes straight to the inner wheel well and is clean and tight its the not cranking after it warm that gets me

make sure it still has the lil ground strap from the engine to the firewall and that it is not all messed up or missing. it mite be your issue, if not that check your fuseable links and relays.

i have been told fusable links but have NO IDEA what the are or where to find them

anyone? any help would be great i have to get it fixed

Check and make sure the terminals on the outside fuse box is clean.....these trucks arent linked..they use the outter fuse box instead of fusable links

Thanks for the help todd it turns out the ground strap from the valve cover to the fire wall was my problem