2006 Dakota 3.7L 175,000 miles. Misfires on all cylinders when under load. Idles fine and does great putting around town. I replaced all plugs with correct gap made no difference.
Truck will actually slow down when going up a hill with throttle all the way open. Cant seem to figure out whats wrong with it some advice please?

 

I will move this to the 3rd Generation Dakota Sub-Forum.

 

sounds like you have a bad cat or even a bad 02 sensor