Sounds like fuel injectorss leaking down, I have seen check valves in fuel pump, accumulator, cause these symptoms also. First connect fuel pressure gauges to the vehicle, then run car to 80c . After vehicle is warm watch fuel pressure and see is it drops .If it does how much and over how long? Make sure proper diagnosis before replacing distributor. The fuel distributor common problems are improper flow, leaking from plunger seal , when replacing it has to be set up properly not just put on. Ask him about these things before spending$$$. I have one but I am not parting out car until january.