i am having starting issues from a dirty Throttle Body (TB).

It has already had a relatively quick clean with some carb cleaner and tissue (TB removed from the car by the AA man, cleaned and refitted).

2 weeks later, the issues have returned, so it obviously needs a really good clean.

Is it OK to soak the TB overnight in a bucket of carb cleaner?

Obviously, the electrical leads will be removed and not soaked, but will the rubber inside the TB survive the carb cleaner unharmed?

errr diesel don't have a throttle body. Do you mean the EGR valve? - the thing between the pipe from the intercooler and the inlet manifold. If so the thingy that operates the valve may not like being soaked in carb cleaner. There is a guide on cleaning out the EGR on here somewhere.

yeah thats what i mean, its the valve underneath the EGR that gets gunked up with oil/carbon sludge and stops the valve opening nicely at startup.