When i start my escort when the motor is warm oh when its hot outside ...i start it climb to 1900rpm and fall to near the 0 and sometime it stall ... sometime not , when it does not stall , it keep searching a good idle rom for infinite time ... goes up and down between 400 and 1000. Do you know that piece i have to change or clean ??? the gaz , air , oil filters are new the pvc valve is new so what can i do ?? the vacuum lines goes to a little thing ... seem to be a coil with a grey cap and a foam filter ... what is this piece ?????

That one piece you mention, I'd have to know where it's located, but from what you're saying I think the problem may lie in your Mass Airflow Sensor or your AIT sensor... when I removed those for kicks I had the same problem.

Hehehe I found the problem !! it was thwe IAC ... i went to the scrap yard and asked the dude and i put a new one and now it work well :)