I have a little problem with my car that is annoying me lately. My car is a Toyota Corolla from 1994 with the 1.6, 4-AFE engine. Completely standard, no tuning whatsoever.

The problem occurs when the engine is cold and at idle speed.

Currently the Idle speed is going up and down at 900- 1050 RPM. It should be around 1500 RPM or higher, not sure how high though. The sparkplugs and oil + filter are resenly replaced. The car drives and feels normal and there are no warninglights flashing in the dashboard.

My question is: what is could be causing this? And what do I need to clean/replace/fix in order to get rid of this problem(as cheaply as possible)?

The idle speed control valve is probably clogged up.

If that was a sentra I would say the above, or a vacuum leak

I think on the older Toyota's the cold idle speed control is handled by a wax pellet valve in the throttle body with no electronics.

Thank you for the quick replies.
I don't know much about the tech-part of cars and all the tools and stuff to use, so I think I'll follow Smartbomb's advice since it sounds relatively easy and cheap.

But what kind of cleaner should I use, or not use, to clean the valve and throttlebody?
I live in Holland, so I probably can't buy any brands of cleaners you have in America.

some sort of carburetor cleaner. The idle control valve port is on the bottom of the throttle body I am pretty sure. The wax pellet valve has water lines going to it.

Ok, carburetor cleaner has been noted down. I'll start working on the problem when the weather is a bit better. - 5 degree Celcius is a bit to cold.
But it gives me time to plan the whole operation.

Thank you for the much needed information!

Did you figure this one out? I have the exact same symptoms. Also my truck runs cold at highway speeds, I dont know if it is related I have a 4'' body lift that could be cooling it off.

I'm very sorry for the late reply. The weather here in the Netherlands wasn't good enough to start working on the problem until a week ago.
But yes, i have cleaned the throttle body and idle control valve. It was a bit hard for someone like me that has no technical knowledge nor any talent.
The result is good though. The engine runs perfectly idle.

But i have no idea what could be cause of your truck running cold at those speeds. Maybe a sensor thats broken?