1996 Ford Escort Cold start surging, when coming down from

I have replaced the Idle Air Control Valve and no response, it only does it when cold. I am going to check for a plugged converter again, also when hot the rpm doesn't come down right away it slowly comes down to idle with no surge. I cleaned the intake with spray in cleaner and it seems to throttle better but still same problem. No engine check light yet.

Hi, Bob, Ken
I checked the vacuum again, I got, at a somewhat rough idle 18.5 in Hg to 19 in Hg. Then at 2500RPM was 20 in Hg it dropped under acceleration down to about 15 in Hg then recovered to 20 in Hg and held that reading without going up or down. So I think by this reading my converter is fine. I am trying to get a code reader to check if the check engine light came on then went out and stored a code. Because no check light yet. I am leaning towards the throttle position or MAF but MAF resistance checks out within the normal range and resistance changes with no lag time.
Jeff

I cleaned the maf sensor no change. I managed to get another code reader. Still no codes, but, I cannot get the o2 sensor heated o2 sensor monitors and cat monitor to run. I managed to get all the rest to say done on the code reader. Why is the monitors not running I am using the drive mode set by ford.
Jeff

I was able to have all the monitors check in and run and done. No codes at all, but I did notice the car runs very smooth now. I think when I had the o2 sensors, idle air control valve changed awhile ago the PCM was not cleared properly. So I do not know if that will make any difference or not, maybe it will not allow the PCM to return to it's original fuel tables. Any ideas?

Thanks I will let you know if things change. I have to drive the car again. Thanks alot for your help. It`s not easy some times working with this obdII computer cars.