Ok, the next thing is a little harder to test since you don't have a scan tool. On the throttlebody, you have an Idle Air Control motor. It is located as #5 in this diagram.
I am attaching a description of what this device does. It has a tapered pintle that closes of an air passage then opens up the cap to regulate a specific idle speed. If that pintle is getting stuck into the seat or the motor is getting stuck not allowing it to retract, it could be causing your issue. Again with out a scan tool, it's impossible to operate. You can remove the 2 bolts and remove it. The pintle and seat get dirty like the throttlebody, so clean them and let's see what happens. Do not push the IAC in, or you'll have to drive it to allow it to move back into it's proper position.
The Idle Air Control (IAC) valve is located in the throttle body of both the Throttle Bowl Injection (TBI) and the multi-port fuel injection (MFI) Systems. The IAC valve consists of a movable pintle, driven by a gear attached to an electric motor called a stepper motor. The IAC valve motor is a 2-phase bi-polar permanent magnet stepper motor that is capable of highly accurate rotation, or movement, every time the polarity of a winding is changed. This change in polarity can be seen when observing a test lamp connected between ground or B+ and an IAC valve circuit while the PCM is attempting to change engine RPM. The test lamp will flash ON or OFF each time the polarity is changed. The Powertrain Control Module (PCM) does not use a physical sensor in order to determine the IAC pintle position, but uses a predicted number of counts. One count represents one change in the polarity, which equals one step of the stepper motor. The PCM counts the steps it has commanded in order to determine the IAC pintle position. The PCM uses the IAC valve in order to control the engine idle speed. The PCM does this by changing the pintle position in the idle air passage of the throttle body. This procedure varies the air flow around the throttle plate when the throttle is closed. In order to determine the desired position of the IAC pintle at idle or during deceleration, the PCM refers to the following inputs:
- The engine RPM
- The battery voltage
- The air temperature
- The engine coolant temperature
- The throttle position sensor angle
- The engine load
- The vehicle speed
When the ignition key is turned OFF after an ignition cycle, the PCM will first seat the IAC pintle in the air bypass bore and then retract the pintle a predetermined number of counts in order to allow the proper amount of air to bypass the throttle plate for engine start-up. This procedure is known as an IAC reset.