RMR Z-28

Been awhile since I been around. Sold my z-28 to Dad a year ago. But now he has a recently developing issue I'm looking for help doctoring. It is still the Lt-1 with vortech S trim running 8lbs boost and other sig line mods.

Once the car is warmed up and not idling higher do to cold start, the idle is low and you have to feather it at the stop light. Keeping the rpm about 1K. On occasion, it dies as you try to take off. You can restart right away and be fine. But you never know when its going to do it. When it tries to die under these circumstances, trying to save it with the throttle yields no noticeable reaction.

the issue has got him in trouble in traffic a few times. I realize this is likely not sufficient detail, but the local shop has been unsuccessful. My old mechanic in Colorado thinks ... EGR sticking ...vacuum leak ....fuel pump. Looking for thoughts.