Good Day, my Corsa is got a high Idling and replaced all sensors on intake and throttle. Still Idling high and workshop light came on. What can the problem be. Please assist me - Thank you.

I would look for a vacuum leak. somewhere between the throttle body and the lower intake manifold.

have the OBD read may need codes clearing

the common problem is the engine coolant temp sensor or connector

Hi maybe check if there isnt a vacuum pipe off or damaged near the intake manifold

It sounds to me like you might have a large vacuum leak letting unmetered air into the engine. Listen for a sucking noise with the engine idling and see if you can find a broken vacuum line or maybe a hose that has been left off.

If the idle speed is VERY high (over 1000 rpm), check for broken vacuum hoses first, then check the EGR. Sometimes the EGR sensor assembly plastic becomes brittle and breaks, leaving a wide open hole into the intake.
Sadly, a common problem with these mid-90s Buicks is a cracked intake manifold. Did the car overheat recently? If so, have the intake manifold checked for a crack.

A high idle usually means air is entering the intake from an abnormal source. Is the throttle plate closing completely ?
Do you have any vac leaks ?

it could be the tps, that is a prime candidate if the IAC is good-and you can check the intake for leaks (common on 3.5's) by taking a spray can of throttle body cleaner and spraying around the base of the intake runners, and the throttle body - listen for changes in idle while doing this.

should be ok because a thing called a zena diode in the alternator should have protected the alternator

Check for a vacuum leak around the intake manifold area.It could also be something to do with any of the sensors mounted on the intake manifold,although they should set a trouble code.Manifold air pressure sensor,throttle position sensor,mass air flow sensor,idle air control sensor,etc.Take some brake cleaner or WD 40 and while engine is idling,spray around the intake manifold.If the engine speed goes up or down in relation to your spraying,that's the area of the vacuum leak.Good luck.