Your Escort's rough idle is a problem but in the pantheon of automotive issues it is certainly a very minor one and, thankfully, relatively cheap and easy to fix. The most difficult part of the process is identifying the precise culprit behind your car's rough idle. The problem could lie in a multitude of components: PCV valve, Idle Air Control Valve, Ignition coil, spark plugs, ignition wires, a vacuum leak in the intake piping or the EGR valve. Have a trained mechanic inspect each one of these units and replace the faulty parts as necessary. The cost of these parts from a discounted OEM ford parts e-tailer range from $16 for the spark plugs to about $60 for an EGR valve. Of course, the dealership would charge more for the same parts so it always pays to shop around!
Keep us posted on the situation shooki!