2000 Explorer Sport 4.0 SOHC lacks power @ operating temperature

Once warmed up my Explorer looses power, will not rev-up, will not go any faster than about 25 mph, then it will go for about 20 or so seconds and do it again. No codes. Feels like its choking or not getting any gas. HELP. Changed Air filter and Fuel filter no change.

Can you hook up a fuel pressure testing gauge and observe fuel pressure from cold start up to normal operating temp while driving. Fuel pumps can and will loose pressure when operating for 20-30 minutes if internally worn.

Prior to reaching operating temp. you can accelerate over 25 mph ?

Once warm can you slowly accelerate over 25 mph ?

Pull the vacuum line off the fuel pressure regulator and see if there is fuel present.

Definetly try the fuel pressure test suggested by tempfixit.

Have you checked your MAF sensor ? Check the two little filament looking wires to see if they are burnt or dirty.

Prior to reaching operating temp. you can accelerate over 25 mph ? Yes full power

Once warm can you slowly accelerate over 25 mph ? This problem can be intermitten at times. I have a 33 mile commute thru the desert, in the morning no problems, in the afternoon I drive about 15 to 20 miles and then have problems (feels like its being choked). After limping thru the desert with misfires and me trying anything possible from drivers seat. finally produced a code (p1131)

Pull the vacuum line off the fuel pressure regulator and see if there is fuel present. ok

Definetly try the fuel pressure test suggested by tempfixit. ok

Have you checked your MAF sensor ? Check the two little filament looking wires to see if they are burnt or dirty. no but I will