OVP didn't do a thing for mine, which was acting almost identical, even after the big vac leak was fixed. If the ABS light isn't on, or it's not exhibiting any other OVP signs, I'd look elsewhere first. New EHA and getting that tuned in properly, then adjusting the fuel injection was the final fix for me. The O2 sensor helped, the injectors probably needed replacing, anyway. I put new idle control valve hoses on it, too. Nothing totally fixed the idle issue until I did the EHA. Took a while of taking it off, adjusting it, putting it back on, etc... but once I got it dialed in right, the car ran perfectly and has ever since.