c class 220 cdi smoking and limp mode
 

Hi everyone, I need some advice. My 53 plate c220 cdi started smoking six weeks ago, a few days ago the engine managment light came on and the car went into limp mode, I took it to a friend who is a mechanic and the code reader came up with p0123 which said it was the accelerator pedal position censer, I bought a brand new pedal unit from MB but it didn't sort it out. I took it to another mechanic who plugged in a better computer it came up with two faults code p2359 boost pressure control and p2511 exhaust gas recirculation monitoring malfunction. He cleard the codes and I drove the car after 5 mins it went into limp mode so we put it on the computer again and it came up with one fault which was the egr valve again. We took the egr out and cleaned it but after five minutes it went into limp mode again. Question I don't want to buy an egr valve if there is somthing else causing the problem, I read on another forum that a car had the same problem and he changed the egr and the air flow censor and it turned out to be a blocked cat, anothe had an air leak.
There you go folks what do you think
Please help I'm not sleeping very well as I keep on having a nightmare that a bloke from Mercedeshttp://images.intellitxt.com/ast/adTypes/2_bing.gif is handing me a bill as long as osama bin ladens beard
Bren x