A simple tool that can tell you so much.

This unit can be secured to the countertop, or held in a bench vice, then each end of the ignition wire is pushed onto the tester and the ohmmeter will read resistance. 

I suggest tugging and twisting the wires while watching the meter to show any signs of increased resistance that have to be investigated further.

I can tell you this has saved us alot of grief over the years.

Avail a couple of ways:

$80.00 Plug Wire Testing Tool
 (you supply multi-meter)