2000 Pontiac Grand Am P0113 is the OBDII code.

Here is the info you are looking for, I've had a few of these with this problem, follow this info:This condition may be caused by a broken wire at the intake air temperature (IAT ) sensor connector. The break may not be readily apparent as the insulation may be intact.

Correction
If routine diagnosis leads to a broken wire at the IAT sensor connector, replace the connector as follows:

Remove the tape from the engine harness convoluted tube where the IAT circuit wires join the main engine harness.
Locate/isolate the 2 IAT wires within the engine harness.
Disconnect the IAT connector from the IAT sensor.
Remove the tape from the IAT and MAF (mass air flow) sensor wires to allow removal of the IAT wires.
Important: Before cutting the IAT circuit wires, it will be necessary to determine the proper length. You need to add 38 mm - 50 mm (1.5 in - 2.0 in) to the length of the wire going to the IAT. Also, when cutting the IAT circuit wires, it is important that the wires are cut in a manner that will not create a large mass. Stagger the cuts and install the connector kit. Original connector cavity "A" has a red wire and cavity "B" has a tan wire. Make sure cavity "A" and cavity "B" wires on the replacement pig tail connector match "A" and "B" wires on the engine harness. This will provide strain relief and prevent recurrence of this concern.

After staggered cuts are made on the IAT wires in the engine harness, strip a small amount of the insulation from both wires and install the kit butt connectors to the bare IAT wires by crimping both.
Stagger the cuts on the pig tail wires to match the IAT engine harness wires.
Strip a small amount of the insulation from the pig tail IAT wire ends. Install and crimp both wires into the open end of the butt connectors that were installed on the engine harness IAT wires.
Heat shrink both IAT butt connectors and let the wires cool off.
After cool down is completed, the harness can be neatly taped with electrical tape.
Install the IAT connector on the IAT sensor.
Clear the codes.
Here is the part# for the pig tail 12102620
you can get this part at your local friendly GM dealer. Please post back if this fixes it.

P0113 its intake air temperature sensor
located before the throttle body most common that we have see it is disconnected (two wire plug )
or its not plugged all the way in
located after the air filter and before the throttle body
check it out
what I think you have changed is the idle air control valve
check it out good luck