95 Corolla idle problems

If the battery is left in a discharged state for a long time, it will become sulfated and will lose its ability to hold a charge.

This is normal. It should go up 100 to 200 PPM when you move the steering wheel if you have power steering.

There is no "fast idle valve" but there is an idle air control (IAC) valve. It is not the only possible cause, but in 90 to 95% of the vehicles with the symptoms you are describing, a bad IAC valve is the cause.

You can try cleaning it with carburetor cleaner - if it is bad, you have nothing to lose by trying to clean it.

As Ray noted, it is likely the IAC valve. Go here....

Go to the appropriate Toyota forum and do a search for IAC or Idle Air Control. You'll find many posts on how to clean it. I cleaned the one on the wife's '93 V6 Camry with about three squirts from a $.99 can of spray carb cleaner from KMart. Problem solved. FWIW YMMV

3 weeks is a long enough time to cause sulfation?

Yes, I know. I think it's an indication that the electrically controlled idle valve (EIAC) is working properly.

Isn't there a thermo-wax activated valve (fast idle valve) in addition to the electrically controlled one? I think there is, since there are coolant hoses going in.

Maybe not completely, but the process will start in time.

I have not studied a 95 Corolla in particular; I am only going by other cars I am familiar with and a general idea of how Toyota EFI systems work. I do not recall any valve with coolant hoses passing through except for the heater control valve, and a thermo-wax activated fast idle valve would be redundant. The coolant temperature sensor tells the ECU what coolant temp is and the idle air control valve and injector pulse duration control idle speed.

Some updates: I sprayed some WD40 into the idle air port, and cleaned the excess oil with a paper towel (a small piece of paper fell in, I hope it wont ruin the engine...)

This seems to have released the stuck IAC valve, since now it starts with higher idle speed (800) when cold, but runs very low when warm (500). I assume the fact that the valve was stuck got the IAC bimetallic coil (is there such?) out of spec.

So I decided to adjust a bit the idle stop screw, idle speed is now ok. Will this cause any problems?

In the future, use efi/carb cleaner or isporopyl alcohol. The film left behind by WD-40 can attract dirt.

You did not mention whether you have a manual or an automatic transmission. The idle specifications differ - vehicles with a manual transmisison have a lower idle speed. The correct idle speed may be listed on a label under the hood.

I have not studied the inner workings of the IAC so I can't answer whether it got out of spec or no. My guess is the answer is no.

No.