my car does the same issue but as im diagnosing it,its looking more like a fuel issue,im replacing the fuel injector sensor on top of the cylinder head all the way in the back of the cylinder head.if its surging there may be a vacum leak,or check the fuel pressure relay,it could be anything even the vacum leak around the fuel pressure regulator.good luck, check all your visible vacum lines make sure none are snaped they are hard brittle plastica lines another thing that will case a surging idle is the idle control calve you can disconect it take the botom off and the have someone plug it in watch it and turn the key on,watch the valve it should move if it doesnt then soak it in carb cleaner if this doesnt work replace it,it looks like a big silver d cellbattery with 2 black pipes off the side,there are all issues you wanna check into.good luck,of one more thing check to make sure the ovp was recently replaced,it stands for overload voltade protector