I don't know if this will help.. or its just a noob answer.. but..
The last time when i was driving the celica, power got cut from my car.. rev's were sluggish, hard to get above 4k rpm, boost wasn't coming in.. and yes, in the middle of driving the car died as well..
Turned out to be a stuffed alternator as the car was low on battery therefore all these problems..
Guess it won't hurt to just use a multimeter and check ur alternator too while ur at it..
My2c
Bernard