My 1992 Loyale recently started acting up. The normal engine idle after warming up went from its usual 900 rpm to around 2200 rpm. The engine runs a little rough with some hesitation occasionly and is running rich. I can not find any vacuum leaks and have replaced the O2 sensor with no luck. Would my next step be the fuel pressure regulator and if so, where is it located?

SOURCE: 1992 gmc chevy 350 wont idle when warm

This could be a number of things but i think that your problem sounds like a vacuum leak or an EGR problem. Try listening for leaks and try un-plugging the EGR solenoid valve one time.

SOURCE: I have a 1992 ford f150. Diagnostics show SPOUT

take an ohm meter and make sure you have continuity in the wires running to computer, the wires looking ok doesnt mean anything, they can be broken under the insulation and you wouldnt know without testing

SOURCE: Rough idle stalls and some times engine dies.P0300

a car that idles rough and clears up is the sure sign of an o2 sensor shorted this may not give a code if the short in the sensor is bad the computer will eliminate its input to protect itself

SOURCE: 94 toyota land cruiser runs rich, rough idle, no power

You have a fuel injected car. Things that can cause too rich would be a bad altitude sensor like the map or mass air flow depending on which one you have.
Anything that would cause excess air to go into the exhaust system like a cracked exhaust pipe before the 02 sensor, or low compression, or a stuck open pcv valve, intake gaskets, throttle body base gasket.
Or a Throttle position sensor which is telling the computer you foot is on the gas when it is not.
Its possible you have a bad PCM,, or coolant temp sensor saying the motor is still cold as its warming up.
Its possible you have a vacuum hose somewhere on the engine with a big crack in it or its just inplugged and you dont see it.

But my first guess would be possibly a bad computer.
Try creating a big vacuum leak when its loading up. It should run better.

Also if you have an egr valve it could be stuck open a little causing excess air or an idle air control valve stuck open.

Does it clean up if you rev it up or does it blow black smoke reved and at idle. This could point towards the altitude sensor.