Our Sequoia Scared The $#@! Out Of Me Options

[Baldy]

Our '01 Sequoia has 93k miles and started sporadically (once a week to once a month) scaring the heck out of my wife but this weekend it finally happened to me. Driving along, all of a sudden the car shudders, as if it's turning itself off, the brakes & power steering go out and there is beeping and the TRAC lights on the dash come on but then it comes back to life almost as quickly. I was somewhat skeptical of my wife's description of the problem. The dealership already put in a new "brake booster" for $1200 (thank god for the extended warranty) but that didn't fix it since yesterday it happened to me twice within about 5 seconds - I was doing 70 on the interstate so I just focused on staying in my lane and after a second or two it returned to normal, except that the TRAC lights stayed on until we reached our destination. Drove home 3 hrs. today with no problems. Any ideas?