The engine in my 240D will not stop running after the ignition is switched off. Initially after switching off the ignition ,the engine ran on for about 5 seconds, after some time it would not switch off at all. I have changed the vacume pump at the front of the engine. No success, the problem persists. The vacume connections at the ignition end seem to be OK. All the pipelines and connections look to be fine. no sign of any leaks anywhere. Any suggested solutions welcome. Thanks. Jim