1999 crown vic keeps getting air locked at the fuel rail?

check egr valve --cat converter

Sounds like a fuel system bleed down problem . Inside the fuel pump is a check valve that suppose to keep fuel pressure in the fuel lines ,injector fuel rail's etc.... when this check valve is bad it allows fuel to drain back into the gas tank . This could be your problem , but without testing this is just a guess . Consider taking it to a qualified repair shop an have it tested ,or buy a fuel pressure tester an check it yourself . Video's on youtube showing how to do it .

there is definately a fuel problem, not getting to engine. check fuel rail for fuel with key in the on position, then check power for fuel injectors, (fuses)

most likely fuel filter and/or pump. check pressure at fuel rail after you replace filter and bleed all air...

If it is fuel injected, the fuel filter is located under the car, on the inside of the right frame rail, under the drivers seat.

they are pressure fit in place. and they are pried out
on the 4.6 litre. if you want to bleed off the fuel pressure,on the fuel rail is a clip that is moved first,and then the fuel line can be disconnected.be careful,the spray is under pressure.cover it with a rag

have look at ur wires that is caming from the car in to the coil it self

purge the pressure at the fuel rail on the engine to relieve the pressure.remove the two bolts near the rear axle at the gas tank straps,lower slowly and unplug the lines and sender wires.that simple.

I hope you have replaced the fuel filter. Every 30000. I took the one off my moms Vic.and we could not blow through it.
I hope this helps you.

The fuel filter is located under the vehicle on the inner side of the left (driver side) frame rail.

Should look like the image below: