MudTrucker

Hello all I was told by a friend that the reason why the 4.0's are hard to start sometimes and lops for the first few seconds is because of loss of fuel pressure. So I investigated it more and he told me that the schrader valve on the fuel rail begins to leak and brings air back into the system even though the cap is on the valve. So I pulled the cap and pushed the valve down and sure enough there was hardly any fuel pressure so I was wondering if maybe anyone else has had this problem and fixed it by putting a new schrader valve in. It also does the same thing if I crank it up and then let it sit for about 10 mins. By the way I pulled the valve out and the color of the rubber on the valve was blue does this mean if I do replace it I have to get another one with the blue rubber for fuel or can I go to a tire store and ask them for a core? I used to work for a tire store and most of the schraders I saw in cores were red rubber.