On my '86, the big positive wire on the alternator goes to a black plastic
junction box mounted on the firewall just above the thermostat housing.
Inside the junction box, the wire is bolted to a stud which is the main
connection point between the battery and the alternator/starter motor. I
found this point to be corroded and the resistance was causing the
connection to heat up. This is the most likely spot to cause a big drop in
current/voltage going to the engine from the battery. The fact that you only
have problems when starting makes it seem likely that the battery does not
have a clean path to (or thru) the engine compartment. Once the engine is
running, all the current is supplied by the alternator.

On 1/27/06, Wesley Pegden <wes@cs.uchicago.edu> wrote:
>
> Today I tried a new ignition switch and changed out the transmission
> ground strap.  Neither fixed the problem.  I don't have any ideas past
> the starter at this point.  I also tried jumping the battery, as some
> have suggested my problem might still be a bad battery.  No dice.
>
>
> -Wes
>
> Roger Sisler wrote:
> > ground straps, ignition switch plug,then take your new starter to an
> > advance auto parts store and have them test it for free.
> >
> >
>