i need help. twice now ,my volvo has only been able to go 15 mph. it happened when i was running errands and tried to accelerate. i pushed the gas pedal with virtually no effect. after say 20 feet i was able to go 15 mph. in the message window it read, "reduced performance". after limping home, and a good rest the car functioned again as usual. i called the repair center. they told me to bring it in, that they could determine and repair the problem in spite of its periodic nature. wrong. the comuter found nothing and it drove normally. they wanted to charge me $85.
my larger concern is that the problem has neither been diagnosed or repaired. i have no idea what to do. today all is normal. has anyone else experienced an issue like this?

 

Sounds like the throttle body is getting ready to go.