My 89 245DL has developed a strange starting problem and is getting costly chasing parts. It starts and revs high but then the idle drops and now that it's very cold outside the engine dies. I have replaced the idle control valve, temp sensor, and the E-Prom (computer chip) in the control module. There are no error codes. Another issue that may or may not have any bearing is that when low on fuel, it takes a bit more cranking for it to start. Once it is running, it's never run better. Since it starts at a high rev, I believe the cold start valve is working, but I don't understand the sharp drop in idle speed. Could it be a fuel pressure issue? Is there any way to test the pressure regulator? Any help would be greatly appreciated.