just really unstable idle....car shakes like **** when it drops to idle speed....and generally itll idle at like a grand....once in a blue moon it actually goes down to the correct speed and when it does it just doesnt seem right

anyone know what the computer does if you take the secondary O2 sensor out of the exhaust and just leave it dangling? the moron that swapped the engine just left it out cause of the header. he said it would richen it up just a little but i really think it is too much i mean wtf a 1/4 tank to go across town