1998 Maxima SE, manual tranny. Trying to keep it running forever.

Soon after starting the car, while driving at moderate speed, I experience a skipping that morphs into a violent bucking from the front end. It can feel as if I'm driving over railroad ties -- or as if the wheels are locking intermittently..

The engine runs smoothly.

Disengaging the clutch immediately causes the bucking or skipping to cease.

Even if the bucking is not happening, I can make it happen by disengaging the clutch and then popping it out.

The condition comes and goes on its own for a few miles, but then goes away for the rest of the trip.

The car got a Fidanza flywheel and clutch kit about 45,000 miles ago.

Desperate for recommendations.

Thanks.