this has car given us a lot of grief before. About a month ago we had this same problem

we had the injectors and HP fuel pump checked all was within specs. we tried a hp fuel pressure regulator on it from another car and it worked fine. We installed a new one then and it has worked fine for a month. Now we have the same problem again. It will accasionally shut down while driving or idleing. Sometimes frequently (every km or so) sometimes it will go as far as 60 to 100 km with no prob. It will not always shut off instantly with the key but will run an extra 3 to 4 seconds or so. We suspect a faulty pressure regulator again since the symtoms are identical with the prev occasion. If so what is eating these regulators up. If not- any advice? Are we missing something?