Question on Ignition coil 1997 Tahoe

[Tbruz]

Does the ignition coil breakdown over time(1997 to 2015) or is this a "works or doesn't work" type of part?
Pretty certain that the coil in my 97 Tahoe with 140K miles is most likely original and wondering what reduced performance I might be experiencing.
No issues starting, even in our coldest New England mornings(sub zero) and fuel mileage is steady at 14 - 15 MPG.
Thanks
Tbruz

 

[SunlitComet]

If a could fails outright it is obvious obviously. It can leak power which would be indicated by arcing around it to surrounding metal. You would likely see random misfires but it still "worked". If the body of it and its electrical point are clean and show no signs of arcing when running then considerate it good.