Re: 84 crown vic
Well this is what i believe it might be.
For CFI check the voltage on your TPS Module....it should be .98-1.0 volts i do believe. after that i would investigate things like when's the last time the car had a tune up?
plugs, wires, and even the coolant temp sensor can affect the car this way. even after all that it's still a CFI car and will still have eccentricities that are beyond repair...well that is until you convert to carb or swap the engine.
Now as for the idle there is really nothing u can do but try this because sometimes this works, If its always fast, I'd check out the thermo-idle stepper device on the passenger side of the CFI unit. Move the little rod that comes out of the vacuum activated part and make sure its not hung up on anything.
Depending on your climate, this thing isnt even necessary and has been sucessfully removed on a Florida CFI here for example.
So yeah, if this cold-idle thing doesnt look bound up, you can easily adjust the idle down... simmilar to how you do with a carb - but expect it to idle lower for cold starts as well.
Now for EFI clean out your IAC (idle air control) and you should be good to go. you might also check your TPS (throttle position sensor).
but if none of these work give me a little more detail on the car and your problems and i might be able to help you out some more.
Hope this Helped