I have changed sparkplugs, upstream Lamda sensors, and did everything bar a Cherokee good hunting dance......it still has its light on and all I get are the "happy codes". I swear there is a gremlin in the blooming thing! A master's in engineering and defeated by a computer!!!!!
My 54 Xtype estate has a similar problem. I have had all the codes repaired as it was asking for upstream sensors. Reset the computer ....20 minutes of running later light on. Now just showing same codes as your. Jag Gremlin????