Pulsing Lights, Voltage Regulator Problem?

1999 Honda Civic HX, 115K, 1.6L VTEC-E, CVT Trans.
Usually, but not always, approximately 20 miles into my 55 mile commute (70 mph) down I-5, every light on the vehicle will pulse (headlights, taillights, dash, radio, etc.). The pulse fluctuates from very fast to maybe 2 per second at the slowest. The intensity of the pulse also fluctuates and often gets worse the longer I drive. When the pulse is very pronounced, the engine also pulses when I attempt to accelerate, or give it any gas at all. There is little or no noticeable effect to the engine when holding the throttle steady. My first reaction was that it must be the voltage regulator. I have had the alternator tested under load, but it checks out fine. However, I have not been able to get the stupid vehicle to malfunction when I have it tested. I've spent hours driving in circles without the pulse, and the repair techs can't help me if the car isn't malfunctioning when I bring it to them. Can I just replace the voltage regulator, or is it integral to the alternator? Should I just go ahead and replace it without knowing for sure if it is the problem? Is there anything else that could cause this (ignition, computer, relay, etc.)? Thankyou for any help.