There is a ground strap/wire from the right side frame rail, to the alternator area ( prone for coming apart for some strange reason.
Lift up the rear seat bottom, where the battery is located there is a ground strap on the right side where it is bolted to the floor.
Check the connection at the battery also.
Check behind left side front and right front hinge pillar covers for those, "square black boxes" the bolt that attaches them to the pillar are grounds.
Check all relays and fuses. There is an IGN 1 relay and IGN 2 relay I believe.
You could also have possibly a loose connection at the starter or failing starter.