my 03 gmc truck had this "reduced power" come up on it the driver info area, the truck would only idle when this happened. if i turned it off and restarted it it it would run fine for 15 to 20 minutes. took it to the dealer and it was a bad maf. check engine light never came on either.

newer cars when they sense a problem, they just shut the car down so it cant be driven far, just enough power to steer and have brakes. most of the time its sensor related.