I would first look at your power cable from the battery to the starter for corrosion in the cable and also check your ground cables.....do a voltage drop test to see where your resistance is.....what does the battery voltage drop to while cranking? Sounds like corrosion in the cables or a poor ground cable from the block to the battery
This is ONLY to be used to report flooding, spam, advertising and problematic (harassing, abusive or crude) posts.