this is a commen toyota problem, talked about many times over on just as many forums. toyota ground cables are run from the battery to the tin (inner fender) then jump from the inner fender to the motor mount, and to the engine block. ANY corotion in either of these SMALL cables and the starter doesn't work properly. i now inst. a ground cable from the battery strait to the starter, on all my toyotas, and don't have any more starting problems. try this on your truck. a good ground is just as important as a good battery.