I've been hunting for vac leaks for some time now. Rough idle, flares and fades, stumbles in OD low RPM. There is definitely a vac leak at one of the tiny holes around the bottom of the EGR valve disk. Is this normal? I've tested the valve by putting vac on the diaphragm and the valve opens, closes, and holds air pressure. I place finger over one of the holes and there is definitely vac leak. Anybody know? Would this be a likekly cause of the idle issues?