Understanding the appropriate procedure and diagnosis codes for a particular study question is an important part of analyzing Medicare data. These codes are very specific and can change from year to year as new codes are added and others are discontinued.
There is no wear-out factor in the coil itself other than thermal cycling and the damage it may cause. Boots and wires do age, resulting in reduced insulation value over time. The key to correct ignition system diagnosis is to understand the details of how the system you are working on really functions. PAGE:
Take it to a mechanic and find out why the idle is off. There can be multiple reasons. Electrical parts wearing out is common - bad plugs, bad ignition coils, bad battery, bad alternator, bad plugs, bad plug wires, etc. ad nauseum. Fuel system problems are also a common cause of this - bad fuel pump, clogged lines, clogged filter, bad gas (fresh gas and a gas treatment will fix that).