ML320 wont go out of limp mode
 

my 2001 ml320 was driving perfectly fine and out of nowhere one day it started to idle rough everytime it was in park and idling or stopping at a red light and it would start to shake and sound like it would should shutoff anytime.(but it wont)
next morning the engine light came on and next day the esp light came on and it went into limp mode. I took it to mercedes and after a 300$ diagnosis they said it needed a new throttle body actuator. Now that its got a new actuator, the code wont go away and after 5 mins it would go back into limp mode and every other code is gone except for the esp one. I dont know the code for limo mode. Now the mechanic says may be it needs new ecu or some****. someone help me out, i just think hes tryna get money out of me and would like to get some opinions before i make another move.
Note. that i dont drive my ml320 alot and the day it started to idle rough... i took it out for a drive after 3 or 4 weeks. so is it possible that mayb something went wrong cause it didnt move for a long time.?

First of all, when your mechanic says maybe you need a new ECU, it's time to get a new mechanic.

You need the exact code that's causing the ESP light. Whatever is doing that could be putting the car into limp mode. If your ex-mechanic won't divulge that info, get the codes read again elsewhere.

Rough idling could simply be a misfiring cylinder getting shut off. That would ordinarily set a code too.

If you haven't driven it for 4 weeks, low battery voltage is a common cause of limp mode. That can usually be corrected by turning ignition off & rebooting.

problem fixed! hopefully
in my case it was a bad throttle body actuator and even after replacing the actuator, the codes didnt reset cause the wiring going to the ecu was loose and once he tighten'em up... it was able to reset the codes and take in the new actuator. thanks for the help