Need a little help guys. I can cold start my 98 f150 with the 4.2 and it runs fine. After you drive it for a while and turn it off and try to restart it, it starts then dies, it will do this until you rev up the motor to keep it running. I have to drop in gear and get going down the road and then it smooths out and runs fine. I had a mech check the fuel pressure at the rail and it was 19 psi. The book says it is suppose to be 35psi. He said my fuel pump was bad. I installed a fuel pump and it is still doing the same thing yet. Any ideas what to check now? Thanks

 

May want to check the fuel filter

 

Fuel filter or fuel pressure regulator.