My 2003 mercury marquis seems to have a chugging reaction when I reach speed of 40mph

39k miles, and it hasn't had a tune up recently, but has been taken care of with oil changes and etc
done by our ford dealer..My husband passed away and I am trying to maintain things like he did..thank you 39k miles, and it hasn't had a tune up recently, but has been taken care of with oil changes and etc done by our ford dealer..My husband passed away and I am trying to maintain things like he did..thank you

Spark plug replacement should be done as regular maintenance at this point. Other components should be inspected by a Tech. There may be a trouble code stored in the engines computer memory that will allow a Tech to start a diagnosis, and this procedure should be the first thing that is done before any parts are replaced or considered suspect.
I would have the shop take a look at the vehicle. Spark plug replacement should be done as regular maintenance at this point. Other components should be inspected by a Tech. There may be a trouble code stored in the engines computer memory that will allow a Tech to start a diagnosis, and this procedure should be the first thing that is done before any parts are replaced or considered suspect. I would have the shop take a look at the vehicle.