I am fairly new to mercedes and am having a problem with my 190e 2.6.

the car is stalling when it gets up to operating temperature. After searching the forums I have checked the fuel pumps, changed the fuel filter, put in a new mas i bought off ebay and the car still stalls.
Where else do I look to solve this problem?
Is there diagnostic tools avaviable that will point me in the right direction?
Also iif anyone has any wiring diagrams with mas that would be greatly appreciated. Also input from techincans would be greatly appreciated.