I have a 1990 Nissan 240SX. Right now it is not running. It needs a new fuel injector control valve. The part # is 23781-40F18. I found a shop online in New York but can’t get anyone to answer the phone. I appreciate any help you can give me. Thanks

No such thing as a fuel injector control valve. The closest thing would be a fuel pressure regulator.
The part number you sent is for an idle air control valve for a single overhead cam 2.4l KA24E and apparently is discontinued.
You might be able to find one in a junk yard or clean/rebuild yours, or maybe get one from a KA24E from a truck or make one from a KA24DE work.

It might help us if you tell us what the problem is. Then maybe we can point you towards the proper solution

That would be the Idle Air Control Valve. Have you tried cleaning it?

They're quite simple devices and can be taken apart for a cleaning.