1988 535i bmw

After sitting for several hours,when the car is first started it leaks gas from just below the throttle. If it is turned off and then restarted the leak stops even after a couple hours. The injectors and the surrounding area look dry. It has to sit for a certain period of time-8 hours or so-for it to do this. As I said it appears to be coming from under where the throttle and its cable meet. It is the 6 cylinder 4 stroke inline, water cooled with inclined overhead valves and single overhead camshaft. Thanks.