The original owner 2004 Ford Expedition E.B 5.4. It is struggling to Accelerate and it's bad!! HELP!!!

[GlennSullivan]

FUEL PRESSUE TEST

Rent, Buy or go to a shop with a 0-100 psi manual fuel pressure gauge.

Have the engine off.

Find the location of the Schrader valve on the fuel tail. Use a rag to let off the pressure built up in the rail. Screw on the gauge and have someone start the vehicle. Pressure should be above 40psi under all conditions. Low pressure would indicate bad in-tank pump, or clogged sock covering pickup area or possibly clogged fuel line.

 

[mbtech2003]

Unbolt the cats so they are loose drive it. My right one clogged up at 115k miles in my 05.

 

[keiferEXP]

Since you changed all those items, check fuel pressure. Sound like fuel pump, did mine recently not too bad with floor jack.

 

[cecilbridge]

I have a 2004 also. 2 things
1) Check if the Catalytic converters are blocked. Have an exhaust shop check it under acceleration. Normal idle might be OK, but under acceleration it’s blocked.
2) check if the front brake are binding - check calipers/hoses. My expy was having issues accelerating and came to find out the brake was binding. Had to replaced both from calipers and hoses. It’s a 20 year old vehicle so have the front hoses check.

Goodluck

 

[EngineerMike]

You had p301 & p308 misfires on respective cylinders, I didn't see that you replaced boots which can crack & bleed spark away

 

[Michael Philpot]

I had my leftside cats replaced due to a rattle. The right-side cats recently started rattling and I experienced very poor acceleration. I had it replaced and it fixed the issue.

 

[Michael Philpot]

Mine is 07 EB 5.4

 

[revrose48]

My 07 was doing the same thing. I had a tune up. It’s ok now. Try that.

 

[Michael Philpot]

My expy had exhaust coming out when idling. The catalyst was loose and blocking the pipe on the right-side. Since it has single exhaust, you will have exhaust at idle but lower pressure at acceleration from the tailpipe. The pressure before the cats will be very high at acceleration.
As for coil boots... that can definitely cause a misfire resulting in lower acceleration.
I replaced all the coils and boots due to a misfire and high mileage.