At highway speed for an hour or so check engine light comes on and car slows

This is very difficult to diagnose this way. I suggest you take it to a mechanic and get it checked out, best if you can get the car to do this just before taking it in or give them all the information. Please give us a call at 405-265-7617 if you'd like to bring it to us to be checked out

go to Autozone,have them read the codes from the check engine light..post code or codes here,it's free..have them print the codes out for you,that''s free too...just don't buy any parts just yet!

Agre with 'stevierays' suggestion , also post VIN#, and I can check to see what is open as far as warranty extensions etc. for your car. In the mean time , pop the hood and verify that the oil level is correct , please.