No Acceleration after some spirited driving
 

Mom is in Canada and im taking care of her car. Shes got an 02 clk with 65k on it and the car sounds great. However, after some spirited driving i wasnt able to go anywhere, meaning pedal on the floor and engine not reving NO FEEDBACK. I have an appointment with mercedes tom. and im wondering what I'll be lookin forward to. This only happens at a light when i wanna go. So weird..
PS where can i get a new rear tail light at a great price online?
myles