Hi folks. I have had this problem recurring on and off for quite a few years with my 95 VR wagon. Changing the CAS by the agents lasted for less than 50km before it stopped dead again. On my one, the problem is dodgy electrical connections in the loom (verdigris, etc) and poor earthing on the DFI module that the coils sit on. You can actually see the film of corrosion on the bottom of the modue. It is not envirmnomental, as the car lives well inland, and is garaged. Only abt 3,000 km / yr, though. Latest try fix is a marine electrical sealant (lanolin based). Fingers crossed.
I would recommend anyone with this problem to go through connections (particularly the loom joints behind the battery) and clean off the bottom of the DFI and the plate it mounts on.