as fas as the positive cable goes, the voltage drop is most crucial during cranking, thats when it(and the ground cable) are seing the most amps. Check from the center of the batt term' to the center of the B+ term' on the starter, then crank it over. Grounds on the other hand can be a bugger. A bad ground hear, bad ground there and life can get a bit frusterating. Sensors need a good ground to operate properly, the ecm needs a good ground to operate properly, tho, it has some redundent grounds internaly/externaly to compensate for ground issues. Lose damaged and corroded conectors are usualy the ones to blame for many "gosts" in an electrical system. The voltage drop on a ground cable/wire should never be more then like .5 volts, and on a power wire it should be no more then like, i think .o5 volts. I know half a volt doesnt sound like much, but when you add them up through out a circuit then it doesnt take long to cause some problems