93 seria 5.7 wont idle cold 1200 rpm when warm

There are 2 idle specs. One is in gear with brake applied. What is that speed?

I've seen from 500 to 1500 RPM in all the manuals I've been through, depending on the year and application (truck/car). In personal experience, 650-800 RPM is acceptable warm operation range. This will also depend on elevation. Will go up to 1200-1500 RPM for cold starting. I live at about 2000ft and my '86 Pickup 22RE idles at 725-750 like a top after about a 3-4 min warm up @ 1250 RPM if it's cold (<45ish).

I would check the idle air control valve. The computer controls idle speed by regulating the amount of air entering the throttle body by using the valve. It could be sticking or failing.
I am assuming you have a 93 Monte Carlo.

a vaccum leak doesnt normaly cxause a motor to rev-up it would normaly make it idle low and rough. however if its cold it should run between 1200 and 1800 rpm untill its warm its called a fast idle.

between 900 and 1200 rpm after warmed up

you need to replace the throttle position sensor on the intake.

it seems that the auto choke setting is maybe wrong or there is a problem with engine management, or a worn part which is sticking.

when cold, the engine should be higher as the choke will be on but a warm up idle of 1200 seem a bit high i would expect around 800 and then on restart if the engine is warm then the choke should be off but the idle being too low indicates one of the above.

you prob need a coolant temp sensor

Yes could be... also the engine should only idle at about 600 when warmed up and 1200 on cold start up so get it checked out a any good garage...

The bad ecu blew the isc motor