My name is Jim Scudieri I have a 2000 Dodge Neon. It idles rough when I am stoped at a stop light or stop sign. It even does it when in park. If I give the car a little gas with one foot and hold the brake with the otherit smoothes out. But as soon as I let off the gas it goes rough again. I have changed the pluges.wires and air filter and it did not help. My gas milelage is also bad. I get about 250-280 miles per tank. I think it should be closer to 300 milers per tank. The car has 127,500 miles on it.
Thank you,
Jim Scudieri
With the rough idle and with the drop in fuel mileage, you might want to change the thermostat if it’s never been done.
If the thermostat is stuck partially or fully open, the engine management system never goes into the closed loop mode. So the computer thinks the engine is cold all the time. This can result in off throttle roughness out of the engine, and a drop in fuel mileage.
Tester
When you press the gas pedal at idle, you are adding just a little more air to the fuel already going into the engine cylinder. Use Throttle Body Cleaner to clean the idle air control valve passages, the throttle bore and plate. Results?