97 powerstroke power loss
 

I have a 7.3 that loses power then comes back. The cycle is running good for about 20 miles and then it fades to where I can only go about 40mph. Then in another 15 minutes it comes back to normal. Any ideas. Someone did mention a sensor at the front of the engine that may cause this. Any ideas.

Any CEL's during the time of power loss? Any smoke or low boost or anything?

i've never heard of the CPS fading in and out. but i could be wrong. i think there is a recall from ford for the CPS. i'd check for codes. that will be a good start.