Looks like you found your problem. You should be good to go after the new wires. Knock-on-wood

 

problem solved, put new wires on, thanks to all who replied!

 

Identical issue on my 2003 Disco where I was not showing any misfire codes but went extremely sluggish at high RPMs under load. Brought it to my Land Rover Mechanic who has the Land Rover Computer and he said it was showing misfires once it reached 2500 RPMS and said unless it continues misfiring that the computer will not store the code. Mine turned out being the plugs not the wires which were relatively new. I had put in Bosch Platinum Plus 4' plugs about 18 months ago and they were the culprit. My Land Rover Mechanic said they were the wrong plug and replaced them. I had selected them based on recommendations from this board. You live and learn. The main lesson learned here is that just because my ultraguage is not showing codes that does not necessarily mean there is not a misfire happening.