Picked up my '95 XJ6 this morning after having the new steering rack installed. I had previously installed new front end parts so now it's all fresh.
Rides so nice now. Smooooth and tracks straight. Before it was steering like a boat and it took a while for my muscle memory to relax.
I have a check engine light on that indicates the secondary air injector. My mechanic tells me I need a new air pump.

Also, he has a 1996 XJ6 w/ 140,000 miles on it that he has serviced since new.
A customer abandoned the car to him and it's red, faded peeling clear coat and ratty interior.
So he wants to take that engine and transmission and exhaust system and put it in mine.
Mine has almost 200,000 miles on it so it's tempting. I had an auto repair shop replace my upper cam chain in 2018.
Honestly the engine has never been the same since that work. Tried taking it back but they said nothing wrong.
Another mechanic said the engine was done for and I should scrap the car. Didn't believe him and still driving it.
It runs great and makes good power it's just a bit noisy below 2,000 rpm.
I've driven the other Jag my mechanic has and it runs good and quiet. Tempting to do the engine swap.
I've put so much money into mine over the years and would like to give it some more life.

 

If you pull the engine there is a small round seal at the top between engine and trans , overlooked gave someone a pesty very hard to backwork leak

There was a pic of the seal location on the net and think hard to find in the parts diagrams

Keep in mind as you mix the engine TPS and the ECUs there is an orientation to change the ECU to " match " the TPS at closed throttle , this would be a form of a null that gets you in good idle speed

Luck of the draw if swapping gives you a match

To start with do not adjust or loosen the TPSs mounts until you have under your hat what happens

If someone says the engine done for , do a compression test as a spinning starter against the factory new spec as there is an doc and values

There are some simple meter test to see if your TPS and MAF is in value along with verifying the STLT ( mixture ) target zero , the ECT at a value to be in closed loop ( 165 F abouts )

There is a TSB on the timing chain tensioner that when done would have a big cast arrow on it

 

Check this video out. If you have a P0410 code, this should fix your issue.

Keep us posted on progress!