First of all, what trim level and year of escort/tracer are you talking about? There are about 6 different engines used in these cars and you'll get several different answers from us based on which we're familiar with.
This sounds like a vacuum problem to me.
Check your PCV (Positive Crankcase Ventilation) valve first. If you've got a 91-96 LX, it should be located between the engine and the radiator. It is nested into the top of a tube that comes out of the block. A hose then runs from the top of the PCV valve to the top of the intake just after the throttle body. If the valve is acting up, or stuck, it might be causing the crazy idle. You can pull it out by hand and shake it. The valve should slide smoothly as you shake it. If there's any doubt, it can be replaced with a new one for less than $5... or you can try cleaning it out with some lubricating solvent like WD-40.
Also, inspect the rubber intake hose that runs from the airbox (filter box) to the throttle body very carefully for any leaks.
Check for codes first. I've seen a roaming idle caused by everything from a bad crank angle sensor to just a plain jane vacuum leak.
Also, check to see if the engine automatically idles up under load, such as A/C or turning the steering wheel while the car is stopped.
What sometimes happens is that people will mess around with their idle without letting the ECU know, and then that throws off the ECU's perception of the base idle. The proper way to set idles on cars with ISC servos is to usually ground terminals on the diagnostic or OBD connector, then reset the base idle to ~700 using the bypass air screw on the throttle body. I'm assuming you have an LX, and I have no idea how to do it on an LX.
But if I were in your shoes, I'd run to the dealer's and look through their copy of the factory manual and see how it's done. You want to look for the topic "how to set the base idle". Good luck. You'll need it. j/k
If you've got an LX, it's most likely a vac leak. Check the small stuff for vac leaks first.
Does it surge up and down in park or N?
Does it smooth out in gear?
Does it kinda half die at stoplights ocasionally?
Chances are it's the intake manifold gasket at the head. That's what finally fixed my surging problem. A few other members on ERDT have had the same problem, cured by a new intake manifold gasket as well.
Of course make sure you have your bases covered and check the simple stuff before you undergo the intake manifold gasket. Ie, good airfilter, pcv ok, fuel filter not clogged (put a new one on), plugs, IAC is ok, etc. You may also want to check your fuel pressure as well. If it's too low, in-consistant, or the pressure regulator has gone bad, an erratic idle will occur. Re-set the ECU as well.
It's a fair bit of work to change the intake manifold gasket and do it right to avoid problems later on. :wink:
Sirigan: Idle speed is non adjustable on 1.9's, nor is ignition timing in any way.
IAC is right on top of the throttle body, FPR is at the passenger end of the fuel rail. Take the IAC off and make sure it's not plugged with carbon. To check the FPR, other than making sure the vacuum lines are ok, you need a fuel pressure guage.
Are you talking about the throttle stop adjust? If you attempt to change the idle with it, you're actually tipping the throttle in since the TPS would read higher than 0, so you're not really adjusting the idle... at least not as far as the ECU is concerned.
If there was any way to adjust the idle manually, the IAC would just readjust it automatically.