I'm led to believe that the Mk 3 LS400 is prone to cutting out after to long journeys - something I have been victim to - I am also led to believe that the fix for this is to clean the throttle body.
So the other day I set to work, taking a couple of photos on the way I thought I'd share my experience for others.
1st remove the three retaining nuts holding on the engine cover and remove the cover.
The throttle body is located on the left hand side of the engine as you look at it.
The above image is looking directly at the throttle body. Remove the large hose from the front by removing the air box et al as well as small hose at the back on the top of the body.
A skilled mechanic could no doubt remove the whole part. I am not a skilled mechanic and so did this fix wit the part in situ. The wire on the right of the three as seen below comes out easily and will help you move the throttle body away from the engine.
You should now be left with an engine bay looking like this
Using a socket set remove the four bolts securing the throttle body to the engine. It should pull away just enough for you to get in, brake your back and get cleaning!
Now you can turn your attention to getting to work. I only to pictures of before - I forgot after as I was running short on time! Anyway, I used a brush, a cloth, a scourer and a screw driver to get rid of the carbon deposits left on the throttle body. I used engine degreaser which worked well. You could use brake cleaner or indeed carbon cleaner!
When clean refit in reverse order then reset the ECU as described in the other guides