/// Generally irregular idle is unregulated air. Check the dipstick 0-ring. Spray carb cleaner around the intake manifold gasket (Valve Body) while the idle is switching and see if it stops. Check the throttle plate and clean the area around it.

Your comment about a wreck adds an element to your diagnosis problem. Run all wiring in the area of the wreck for damage, cuts, nicks, crimped wires or damaged connectors. Look for any place that paint or high order solvents could have gotten in connectors or melted insulation. Depending on the strength of the hit you could have an air leak almost anywhere on the intake system.