It sounds more like a dirty throttle valve and a slow idle air control motor (IAC). Your car has a throttle switch (on/off) not a throttle position sensor. The switch needs to be closed at idle so that the IAC knows that it is in control of the idle speed. If the throttle valve gets dirty enough it will hold the throttle switch open as well as not allow enough air through the throttle valve to hold a steady base idle. Take the valve off, clean all of the carbon out of it, reinstall it on the manifold with the throttle switch screws left loose and the 8mm nut on the idle speed set screw loose also, clamp off the hose that goes from the air intake hose to the IAC and dial the idle speed set screw until it is at about 540RPM. Lock down the 8mm nut and make sure the idle speed is between 530-550, shut the car off, adjust the throttle switch so it clicks on opening and tighten it down, hook up the throttle linkage and adjust it so the switch clicks on opening and closing, start it back up and make sure the idle is still where it belongs, remove the clamp on the IAC hose and watch the idle jump up to where it belongs, 750-800.

Mark