For a Ford LTD Crown Victoria 1984 5.0 engine, how to drop down the RPMs on the carb idle?

Electric choke thermostat is new and Throtle position sensor is new. Timing is adjusted but the RPMs are still high running at 1400. How can I drop it down to 550?

Would appreciate your help greatly.

It is adjusted with the ac kicker, and 550-75 is right on the money in d with the ebrake set

It has been some years since I have even see a variable venturi carb like you have, if I remember there's a stepper motor that will adjust your idle (a little stem goes in and out where your throttle is connected at the carb) and he is controlled by the PCM. Make sure he is operating by watching it during a cold start or turning the AC on and off. If he is working make sure (if there's one) the adjusting screw is backed down so that the PCM can control it, someone could have cranked it up when it started to fail and the PCM may not be able to lower it. Also, make sure that you pulled the PIP (Profile Ignition Pickup), a little gray plug near your distributor when you set the timing. That will stop the computer from trying to advance timing while you set it (10 degrees Before Top Dead Center ). Also, Look for vacuum leaks around the intake using brake cleaner, Brake cleaner will make the engine reduce speed when you spray it on a leaky spot because it really is not that combustible so it is much safer to do. I actually figured that out on a VV carb 20 years ago because I caught it on fire using starting fluid looking for a high idle problem.

Typically about 700 in Drive is correct. There should be an idle adjustment screw somewhere.

550 is too low. Try for 800.