Idle messed, and speedo no working

Last week i broke my torque arm and after i fixed it, my cars speedo isnt working. not sure if that hasnt anything to do with it or not.

anyways that isnt the main problem, when i start my car it runs fine idle is all good around 900rpm then as soon as i start driving it when i comming to a stop the idle goes down to about 400 and stays there and feels like it wants to stall. it has twice. The check engine light usually comes on after a few minutes and once the check engine light comes on the car starts to idle at stops properly again

any ideas of what might be wrong?

sounds like the VSS or connector/wiring was disconnected/damaged when the torque arm was fixed(no VSS signal to the PCM will do what you are describing)

thanks i may have knocked it with the torque arm, it was a pain to do by myself. ill check that