Was doing about 75 mph on the freeway coming home from work earlier today when all of a sudden the car shudders like someone hit the car from behind. Also felt like a slipping clutch that suddenly catches. After the momentary thud, off you go like nothing happened. Very intermittent as well. Did it three times on the way home and then later on in the evening at much slower city street speed (about 25-30 mph or so). Car is up to date on all service intervals. Has about 115K and engine runs very well. Have had the normal wear stuff replaced (e.g. engine - timing belt and water pump, suspension - boots, tie rod ends, new tires, etc).
Thanks for any feedback regarding what the problem might be.