so I can push on the little plunger in the fast idle valve and it will rev the engine up, but it will never stall. so should I replace that?

 

Take of the snorkel to the throttle body. Start the car and let it get to normal operating temperature. There should be two ports in the throttle body to allow air to bypass. Cover the lower port with your finger. If the idle stabilizes, then the FITV is the likely culprit.

 

it did exactly that. warmed up, drove it around, came back and put it in park, started surging, put my finger over that lower hole and it stabilized.

 

so another valve did not fix the problem. random question. would bypassing the heater core cause this type of behavior?

 

repeat the test where you cover up the port. If this stabilizes the idle again, remove the coolant hoses going to the FITV and check for a blockage.

 

Did you bypass the heater core with or without the temperature-control valve in place? If the valve is there, try closing it (as if you turn the heat down to the cold end of the slider).

If the valve is gone, it might be better to have a restriction in there instead of a wide-open bypass. A wide-open bypass might take all the flow leaving very little flow rate through the FITV.