Why does my 1985 Porsche 944 start and run for 3-4 seconds and then turn off?

I replaced the spark plugs and feul filter. The feul pump is pumping feul to the engine. Could not find any vaccume leaks. I am probably the farthest from being a mechanic but I can read a Childers Maintenance book. Any ideas from you more experienced mechanics?|||Most likely the fuel pressure regulator has gone bad causing fuel pressure to go way above specs. A fuel preesure gauge would be needed to confirm, or go could jus buy a used one and try it. Good luck.|||Sounds to me that its not receiving a spark from the plugs, also check or replace the fuel pump relay or the pump which is under the drivers rear wheel arch, also check the fuse to the pump under the glove box, the board burns up on these and is later replaced with a later type.|||You are running off the fuel injected by the cold start injector an airflow sensor is suspect|||the fuel pump can pump fuel to the engine but it may not have enuff pressure|||check your wheels for air.