1989 1.9 L Ford escort idles too fast, 1500 RPM, supposed to be 720-750 RPM to pass inspection in CA. Replaced idle speed control, made no difference. Has new catalytic converter. Thanks for any help.

The 2.2L of that year would be the 5S-FE engine.
It used an electronic Idle Speed Control Valve.
With all of the intake/vacuum system connected connected, accessories off and the transmission in neutral connect a tachometer. Short terminals TE1 and E1 of the underhood check connector.
Wait for the idle to maintain 1000-1300 RPM for 5 seconds.
If needed adjust the idle adjust screw to an engine speed of 650+-50 RPM.

US Idle is 700+-50 RPM, CA M/T is 800+-50 RPM and CA A/T is 750+-50 RPM.

Remove jumper of E1 and TE1 of the check connector.

idles too fast.
what engine?
what year?

on a gas engine, the idle speed is 100% controlled by PCM at all times. hot.
so its out of control that means the PCM closes the ISC valve.
and RPM will not drop. (its stuck open) or vacuum air leaks
jeeps use speed density EFI system using the MAP sensor.
this means all air leaks on jeeps , cause wild fast idle speeds.
that is all you need to know , to find problem (find leaks)

clean the ISC yet (idle speed control) valve.?

Chech idle adjustment screw, and spark plug gap.

sounds like it could be the idle speed control valve

fast idle speed screw, works off the fast idle cam which the choke adjustment sets, it works together by linkages. This is the raised idle speed setting you need to keep a cold engine running. First you set the idle speed by the idle speed screw with engine at normal operating temperature. Then you set the linkage up so the cam is on a raised step, throttle will be held on that raised step. then you can turn the idle speed screw to get idle at about 1500-1800 rpm. Now when you start engine cold, choke will set the fast idle cam on that raised step- when engine starts and runs it should be running at your fast idle setting. That's how it supposed to work, you just have to get everything adjusted right. I hate carburetors, they never stay adjusted right. Considering their complexity and small mechanical parts, no wonder.

The idle speed is not supposed to be adjustable. It is controlled by the computer.
What you may have is a vac leak, or the throttle cable may not be adjusted correctly.
If the throttle plate is completely closed, and there are no vac leaks, the idle air control valve is supposed to control idle speed by regulating how much air enters the intake.

EGR valve and PDFE sensor control idle speed. The idle speed valve you replace very rarely goes bad.

Sounds like you idle air control valve is starting to mess up. You can actually take this off and clean it with throttle body cleaner and it should help get your idle back to normal. As is sounds the idle air control valve controls how fast/slow your car idles. It is located on the throttle body normally held on with a couple of screws. The throttle body is where the air duct hose coming from the air filter box ends at the engine block. Here is a picture of what you are looking for:
Make sure that you clean the valve portion and not the electrical plug with the throttle body cleaner. Let it air dry or blow lightly with compressed air before putting it back on. Let me know if you have any more questions. Thanks for using FixYa!

PVC valve is not metering air correctly, it will appear ok shaking it but looses it ability to maintain proper position causing a medium to gross vacuum leak.

Hi , i have a 1995 Escort with 1.9 4 cyl engine , at cold start the engine revs ok but as it get warmer it start to idle rought and die , with a scantool the o2 sensor always reed lean at idle , after checking fuel pressure , air mass meter , EGR valve , and potential vacuum leak at intake and hoses , its the PCV valve that give me that problem , as i remove the pipe with the valve there was a whissle noise comming from it , when i block the valve at its tip the whissle noise stop the engine revs smooter and the o2 reads normal , i replace the PCV and its idling good .