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As far as the timing, where should it be? at zero? I've heard of people timing it all the way to -12.
Have you inspected and/or replaced your battery and battery cables... or run any voltage drop tests? Labored cold and hot cranking suggests insufficient voltage. Do you have headers? Do you have any exhaust leaks? Have you verified the ignition timing? Are there any other engine configuration particulars about which you haven't told us?