Mercury Mountaineer rough idle, backfire, and power loss issues despite extensive repairs on Mercury Mountaineer

Some Mercury Mountaineer owners report experiencing issues such as rough idle, backfire, and power loss despite extensive repairs. These problems may be linked to a failing ignition coil, which can cause symptoms like misfires and reduced fuel efficiency. Additionally, fouled or improperly gapped spark plugs are reported to lead to misfiring at low RPM, contributing to rough idling. Some owners also note the potential for vacuum leaks to exacerbate these issues. Problems with the Mass Air Flow (MAF) sensor can result in rough idle and slow acceleration, prompting some to clean or replace it. Furthermore, an imbalance in the air-to-fuel mixture is cited as a factor affecting engine performance, while issues with the Exhaust Gas Recirculation (EGR) valve have been linked to improved idle when the exhaust line is disconnected. Lastly, bad motor mounts may cause shaking during idle, indicating the need for inspection. Addressing these factors could help resolve the performance issues in the Mercury Mountaineer.