Loss of power
 

1997 mountaineer, 5.0, sometimes it runs perfect. Then suddenly it acts as if its out of gas and will only go 10 to 20 mph. Shut it off and wait 60 seconds and it will run fine for a couple of miles and then start again. Even when it acts up the idle is fine. Replaced the fuel pump and filter as well as cleaned out the tank. Checked the fuel pressure and it is good at 30 psi. Checked for codes and got 401 and 402. Cleaned the EGR and replaced the solenoid. All the books say that the car has a DPFE but if it does I can't find it. The decal under the hood does'nt show one either. Did a vacuum check to see if it had an exaust blockage which it didn't. Anyone have an idea where to go from here?
Thanks