John
You have me a little confused. On one hand you say you cannot find the EGR vale and then you say "with the way the carbon is built up etc etc". If you cannot locate the EGR valve how do you know there is a carbon build up." Good luck with removing the inlet manifold, it is not an easy and straight forward job in my opinion.
Whilst you have the intake manifold off you might consider changing other items that are then accessible and may be leading to "rough idle and misfires."
Please update when you have sorted the problem.
Good luck and Best Wishes, Regards, John