What are your RPM at idle once warm up?
When you say rough idle, do you mean it shakes the engine or RPM goes up and down.

There could be numorous reasons for rough idle at warm up, coolant temp. sensor, Oxygen sensor, distributor rotor & cap to name few.
I will start with good cleaning the ICV, it is known to cause all kind of issues with idle.
What is the history of the car, how many miles? regularly maintained ?
Did you tried "Fuel injection cleaner" of any kind, that might help.

Hope it helps

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87 420 SEL
Looking for a nice mid 80's MB diesel.
87 BMW 528e (Sold)
99 TOYOTA 4Runner
1989 Honda Accord (Sold)
1988 Honda Accord (Total)