Our 1990 240DL's engine problem has gotten worse. Previously, it was running lean and hesitating. Check engine light came on, the codes that it gave indicated a lean condition. After driving it awhile longer, it is now at the point that when starting it up, it will run for 2-3 seconds and then die. It will start right up again, but only running a few seconds before dying. I have replaced both fuel pumps and fuel filter. I tried unplugging the hose on the fuel pressure regulator. What else should I check? thanks Mark