Had the check engine light come and it came out to be p1578 which deals with the throttle body. I dont think thats the problem because it has a really rough idle and it doesn't sound like all 8 cylinders are firing. Anyone have this problem?

 

No-one has ever posted that. Also, I cannot find that code as valid for Jaguar cars.

What tool has given you the code and is there any chance that it's been posted incorrectly or communicated incorrectly?

I would not assume it relates to the TB.

Many times a dubious code is caused by a failing battery or poor power/ground.

 

You have the dreaded 4.0L V-8.

Do you know about the timing tensioners and have they been replaced?

It sounds very much like you have jumped time. I hope you are not too late to save the engine.
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Im sorry I did type it wrong, its P1587. I checked the battery and its good but the alternator is not charging well though

 

I dont know what state they are in but I'm pretty sure they haven't been replaced. If that's the case I hope its not too late too, how would I know?

 

Look up the codes info either in JTIS or codes PDF (both free on here) and you'll see it relates to TACM circuitry not the TB

JTIS likely has tests if you look.

 

Sorry but the software for this forum is absolutely terrible and now has been changed to be almost unusable!

I tried for 30 minutes to correctly insert 4 pictures in my answer but it is all screwed up. You can only dump pictures with no control. Terrible software again. I am on several car forums and this one always gives the most problems and is the most difficult to post to and most often has errors when loading.

But you can pull a cam cover off and look at the tensioner. It was bright white plastic when new. It will now be orange/red plastic with cracks. The new updated ones are mostly metal and will hold up.

I have the pictures attached but I could not insert them so they made sense!
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Does anyone know which pdf is for the timing chain? I cant seem to find it in the downloads

 

I checked the tensioners they are the most updated but I did notice they are springy, is that normal?