2000 mercury sable runs rough between 55-60 mph

[bond67]

Hi
I have a 2000 mercury sable with a 3.0. I have replaced the spark plugs, spark plug wires, the dpfe sensor & the egr valve. The vehicle still is idling rough and it surges @ 55-60 mph ( seems like it has a governor restricting it). It did not run like this when I purchased it. I have been to the dealer and they ran a diagnostics and told me it was the spark plugs and wires ( $60.00) and the check engine light came back on. I had it checked out at an independent repair shop (i was charged $45.00) and they said it was the dpfe sensor and the egr valve. I have changed all of the above parts with zero results! It all started when the battery went dead & i replaced the battery. Please HELP!!!

[hughw]

The next thing I would try is run a good enjecter cleaner through the fuel system...dirty enjecters shouldnt give a check engine light...but could cause the rough idle and surge

[beyondloadedSE]

Did you check the alternator?