After adjusting the idle speed (with the screw on ISC)...I read here that it will eventually reset? Now the thread was regarding an EB but I just wanted to make sure it's not the same for an EF.

I have a really s**t idle at normal speed so I upped it to 800rpm which is quite fine ,, I cnt get a fix for few weeks coz im working so I want to know if it will actually hold my idle speed indefinitely? Or will the ECU **learn** around it and turn it back down eventually?

The ECU will always try and get the idle to around 650rpm. But it can only do this if there is enought movement left in the ISC. If the ISC is max'd or min'd out then the ECU cannot reduce or raise the rpm.

If you are concerned simply disconnect the ISC connector and adjust your idle speed (the car will most likely stall until the idle is adjusted). That way it cannot change.

Once everything is fixed you need to put the car into diagnostics with the ISC disconnected and set idle speed to 650 with a 0.75mm feeler between the idle screw and throttle stop.

cheers
Scott