What can be done to make a 1999 escort idle more smoothly?
Try replacing the fuel filter. After every 30,000-60,000 miles depending on how often you drive. It will allow more fuel to the engine and idle more smoothly. This did not help Oxygen sensor is dead. Replace it, but it will not last long if your engine is smoking, or when there's any silicone contamination inside the engine. Don't forget to reset the error codes, otherwise the new sensor may not be noticed by the computer. I had that problem, i simply replaced the PCV Valve, changed my spark plugs, and spark plug wires, and checked my air filter. After doing those steps, i got a 1.5mpg increase, more HP, and smoother run.