Ford added the dual spark plugs because of emissions requirements, so both coil packs need to be working.
The exhaust side coil is used for starting, intake side coil isn't used until engine is running.
So you can often test coils by swapping them, if you get a no start then that coil is bad.
Or if you have an old timing light test if intake side coil is sparking while engine is running.
There are no noticeable effects of a failing intake side coil, other engines run just fine with one coil or coil pack, lol, and so does 2.3l, but it can effect emissions and tach, low RPM reading and will often set a code and turn on CEL.
All fuel injected engines are run richer at idle this prevents overheating of combustion chambers, this also raises HC, but it should stay below requirement for that model year.
1993 should run the AWSF-32PP spark plugs, speced gap is .044, I would increase that to .048, that will give you a more complete burn at idle.
And just a heads up, any time you are using a Ford coil pack system it will be a Waste spark setup, so either run regular copper spark plugs or Double platinum, single platinum is a waste of money on this type of setup and will wear out same as regular copper.
Rule of thumb is larger gap gives better low RPM performance, smaller gap better high RPM performance, the spec of .044 is the middle.
Also what is the idle RPM?
2.3l usually has a higher idle, manual trans 700-750, auto 800
When you get down below 700 the HC will go up.
Dirty injector tips can drip fuel at idle vs spraying it, this will cause higher HC readings as fuel and air are not mixed completely at idle.
Run a can of Seafoam or similar treatment in the fuel tank, this can help clean injector tips.
In my area they fail you if Check engine light(CEL) doesn't come on when it should, so burned out bulb is a no pass, they won't even test vehicle.
Also run a higher ethanol content fuel for the test, E10 is 10% ethanol/90% gasoline, this lowers HC.
HEET is sold in auto parts stores it is an alcohol based product used to remove water from gasoline but also will lower HC.
Just FYI, Gasoline and water don't mix, and water is heavier than gasoline, "bad gas" is often when water in the storage tank(gas station, or last delivery truck) gets pumped up and into your gas tank.
It will settle to the bottom and get sucked up by fuel pump causing rough running, not high HC though.
Ethanol/alcohol does mix with water(H2O), and will still "burn", so running E5 or E10 helps keep gas tank fuel free of water and acts as an anti-freeze during winter months because unmixed water freezes at 32degF, mixed with ethanol it won't freeze until -100degF or more
HEET is sold for this purpose as well.