odd idling problem, im stumped

[fallacious_focus]

i drove to kentucky on wednesday and thursday, i took my time and had no issues at all with the car. on the trip back i took a much more mountainous route than on the way there. i didnt have any problems immediately, but a couple of hours later when i was pulling in to nashville i encounterd some traffic so i went ot downshift and while the clutch was engaged the rpms jumped into the 4Ks. i pulled off the road, restarted and the while the problem was still there it would only raise to a more managable 2K rpm. does anyone know what this could be, i havent done any performance stuff in the last couple of weeks...

[Sponsor]

[fallacious_focus]

i took the car to autozone cause the cel came on.
code: P1506
Idle Air Control Overspeed Error

what exactly does that mean for me? do i need to take my car to a shop or is this something that i can fix on my own?

[Kicknzx3]

iac... sits at the back of the manifold. no big deal