How to tell if i need to replace my distributor or distributor cap on my 1990 ford thunderbird?

i have a 90 model ford thunderbird with the 3.8 v6 how do i tell if the distributor has gone bad or if the distributor cap is bad? And also it is fuel injected.How to tell if i need to replace my distributor or distributor cap on my 1990 ford thunderbird?Look for arcing from terminal to terminal... little lines, signs of wear where the rotor contacts the cap terminals, or obviously, cracks in the plastic. But by the time you get cap and rotor off to inspect them, you might as well replace them anyway.How to tell if i need to replace my distributor or distributor cap on my 1990 ford thunderbird?if you have Q's about the distributor, and if your mechanically inclined, pull the distributor and check for any kind of side play, and play as well. the shaft is bushed and the bushing does wear out over time causing the shaft to "wobble" or "lean" to one side. you will need a micrometer to know just how much play you have, then call a distributor shop and find out what the specs are, auto zone might have those specs, but im not going to run with that. that is kind of out of their realm.How to tell if i need to replace my distributor or distributor cap on my 1990 ford thunderbird?why do you need to replace it ? whats wrong?....id say change to cap and rotor first