#12 just means the battery was disconnected recently. Like maybe when the CD player was installed.
#43, you had at least one plug acting up. And a possible coil.
Might be time for a good tune up. And possibly a coil.
But before anything do the following.
Disconnect the battery for ten minutes. That will clear the codes. Drive it for a couple of days and see if you get a check engine lamp on. No telling how old those codes are.
Least this way you'll find out the current ones if any.
97 Sahara, 74 Renegade, 72 CJ5, 55 Willy's (the Beast) Boss 302, 6:34 gearing, Bose 901 speakers.
God I miss that Jeep. Forgot the kinda Jeep, 80 SX4.