Q: Car jerkin at 40 50mph wen i re hit the gas it goes away..but no service lights are on

An issue like this is not unusual and can be resolved if you request an engine diagnostic. During such a diagnostic, the certified mechanic would come to your location and run through all the possible causes of engine misoperation at speed and those possibilities include exhaust manifold leaks, worn seals or gaskets in the exhaust system, a failing catalytic converter causing exhaust blockages, malfunctioning oxygen sensors, dirty fuel injectors, faulty spark plugs, a faulty mass airflow sensor and vacuum leaks. If you have further questions or concerns, do not hesitate to re-contact YourMechanic because we want you to make the most of your repair dollars and help you to get the best possible results.