Idle on my 1992 cadillac deville is very low

EGR Valve issue (Exhaust Gas Recirculation)

https://www.google.com/search?q=1992+Cadillac+DeVille+Sedan.+error+code+E48

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Not without testing ? Your best bet , take it to a qualified repair shop.

E13: right bank O2 sensor, no data
F48: low refrigerant level in A/C system

Neither of these is likely to cause rough idle, but I would change the sensor.
If that cure it, great.

If not, make sure the vacuum hose on the fuel pressure regulator (at end of fuel rail) is tight at both ends and not cracked or leaking. Then pull the vacuum hose off the regulator and see if there is any fuel in the vacuum hose. If yes, replace regulator.
I also recommend cleaning up the intake side of engine with carb cleaner or equivalent: throttle body, Mass airflow sensor, EGR system, and PCV valve. Make sure EGR valve is operating.

If you have questions, please let me know.


fuel press reg:

I had same problem, and found the problem again in egr, replaced it under warranty and bingo.

THE ENGINE COULD BE GETTING TOO HOT DUE TO STOP UP RADIATOR CORES OR ENGINE BLOCK STOPPED UP WITH RUST RESTRICTING COOLANT FLOW.THERMOSTAT NOT OPENING FULLY AND CHECK FOR LOW COOLANT.

did you change the cap and rotor if so check to make sure you didnt cross a spark plug wire when putting new wires on

try fuel pressure regulator

If by rough you mean it sputters like it's idling too slow, it's most likely the TPS (throttle positioning switch) which controls both the cold and warm idle.
Could also be a MAP sensor. Run the diagnostics test on the car and retrieve the error codes to point you in the right direction. Go to the link below for information on retrieving the self diagnostics on your Caddy. Best of luck.
Greg
http://www.troublecodes.net/cadillac/cadbrom.shtml

cylinder 2 misfire po302

throttle position sensor. or idle control sensor