1990 Ford Tempo

We were driving down the road and it just died. Try to start it and sometimes it will start and run for a few seconds and sounds good and then just dies as if it were not getting fuel or spark. Other times it won't start at all unless you wait for awhile. It is getting fuel in and out of the fuel filter. Spark plugs look good. Changed the ignition switch and the coil. Still not working. What should I do next? Thanks for your help. Mike

1990 Ford Tempo
125449 mileage