Dying at idle?!?
How about starting with these voltage checks and we can try to proceed in an orderly fashion to dig these issues. Please don't skip anything as each step can uncover a problem.
To tackle the cranking issues:
- Check the ground from the battery to the engine and make sure the connections are super clean; use a file, knife, or wire brush to clean them.
- Check the ground from the back of the engine to the chassis up on the firewall to make sure it is clean and a good ground
- Make sure both battery terminal connections have been cleaned with a wire brush; clean both the battery terminals and the connections to a bright shine.
- Measure the battery voltage directly across the + and - terminals.
- Keep the - lead on the - battery terminal and move the + lead to the large lug on the starter relay; see if the same voltage is there as on the battery.
- The move the meter + lead to the large connection on the starter and see if it is the same as the battery voltage.
If the battery voltage is under 12.4 volts or so, then have it charged. A well charged battery should show a good voltage of 12.6 or 12.7.
START tests:
- Put the leads back on the battery terminal directly and have someone turn the key to START. See if the battery voltage changes and note that.
- Then move the + lead of the meter to the big lug on the starter relay and do the same thing.
- Then move the meter + lead to the large brown wire from the starter relay to the starter; See if that jumps to close to battery voltage when the key is turned to START.
Let us know how all the works out.