Normally your car cold starts at 1200-1500 rpm, which drops to drops to 700-800 rpm when coolant temp reaches 85C, also the rpm should sustain either You turn on or off you AC, but if your vehicle don't follow this behavior or having abnormally high or low RPM, this mostly indicates a problem within engine throttle body, that controls the amount of Air that can get into the system.
Throttle body consist of TPM , IAC and a butterfly that can be either controlled electronically or mechanically as being shown here.
All throttle body related problems can be solved without removing it, All you need is WD40/Diesel, Carb Cleaner, toothbrush and piece of cloth.
In Idle position butterfly is closed and a very limited or controlled amount of air is allowed via this hole to other side via that via IAC value, that can be either clogged or jammed.
Similarly the carbon deposits on the sides or groves of the butterfly could allow some unwanted extra air to escape through.