merc e320 cdi 2000 model advise/help

[adaptorman]

h all ive a issiuse with my merc e320 cdi auto , car drives fine cold . but when engines warms up . its lke its in limp mode and wont rev above 2000rpm , any ideas
im also after a posible cheepy fault code reader but none of them on ebay seem to really know , as mine has the round contector in the fusebox , and not the 16pin obd2 oblong type socket , i do have the 16pin to round socket adaptor ,

 

[NW_Merc]

Where are you in the country? There might be a fellow member who has diagnostic equipment who is willing to help