I just got back from the mechanic's shop. He took the top timing belt cover and middle timng belt cover off the motor, and found the problem: the timing belt idler pulley on the lower right side is disintegrating. It's missing large chunks! A fine quality part that lasted for 27,000 miles.
The mechanic wanted $400 to replace the pully. He said the pully costs $60 and the rest is labor. He said I really should also replace the belt, the tensioner and the other two idler pullies, and that would be an extra $200, for a total of $600.
I declined (too expensive). So I had the car towed home just now. I've got my repair manual and some hand tools, and I am going to try to replace the idler pully myself. yikes
