The only thing the regulator does is regulate fuel pressure. The way to test is to watch fuel pressure. All K-Jet systems, including KE rely on absolutely steady fuel pressure.
Large swings in pressure could be your problem, but even if thats the case (easily tested by monitoring fuel pressure), it is still more likely for other components to be the cause. If pressure drops it is more likely a pump, filter, or relay problem than the pressure regulator. The most common problem of regulators is leaking and or too high of pressure which floods the motor. Unless flooding is suspect, I wouldn't think regulator.
Bosch Master, ASE Master, L1
33 years MB technician