idle surge
 

My 01 Elantra 54k miles is surging from 1500 rpm to about 4000 up and down non stop. I had to undo and splice the wiring harness under the left fender to do a body repair. I was very careful to solder and get the wires back to normal [all 25]. As far as I can tell none of these have anything to do with the idle. The car ran fine when I parked it. I dont think any thing just spontaniously broke on its on. What could I have done. Or what controls the idle. Wiring diagram would help.