Recently my V12 XJS developed a rough idle, it starts fine and when on the choke runs well, but once warmed up it idles rough and also if you hit the gas hard it hiccups before getting power, upper register runs fine.

Anyone have any ideas?

Submitted by No1inTex@verizon.net on Tue, 07/29/2014 - 20:15

John,
Check the vacuum hoses for cracks etc. Also see if the extra-air idle control is moving as it should. It's common for this part to get stuck and cause hunting. It is easily accessed and replacing will be worthwhile.
I hope this helps. Others may have ideas as well.
Don