3.4L 100xxx miles

Recently experiencing loss of power when driving. Accelerates fine at low speeds but at over 50 mph its hard to get it to speed up or maintain speed. Check engine light has not come on and there are no codes.
Where should I start looking?

 

Any vacuum leaks? When I had a vacuum leak in the engine bay, I had no troubles accelerating, but when higher speeds 50+, it had trouble gaining speed.

I'd check to hear any hissing noises under your hood..while you're there, check for any debris behind your driver side headlight that might be blocking your intake opening.

It's hard to tell (for me at least) from given decription, but I'd start with that.

 

Another thought, possibly your cat is clogged, after driving look under the car to see if its glowing red at all.

 

When was you're last tune up performed?