Ouch....sounds like it is. That was my problem
(years ago); coolant disappearing slowly and
6 misfire. Not an easy fix.
In my present case it turned out to be coil pack.
I ended up paying someone to fix it.
Why? Because my original coil pack was bad.
I bought a replacement
coil pack at autozone. Still had a misfire.
So I figured it wasn't coil. After paying
speciality diag shop they found that
my replacement coil was ALSO BAD!!
Replaced with motorcraft coil and now
all better (but I'm poorer)
lesson? Cheap no-name PRC electrical parts suck.