As the above question states, Is it miles? or just time (Days)? I just changed the plugs, and was thinking maybe I need to change the wires... These wires have 3 summers and 2300 miles?
Do you own an ohm meter? Can you google up how many ohms /ft the wire is suppose to have. Then put the leads on each end and measure. Measure the length of the wire and do the math. If the ohms don't match the spec, you need to replace.