This may be my first major issue with my 5.4L F150. It has about 111,000 miles on it and has just recently started to exhibit a sluggish acceleration. It feels like someone is pulling on the rear bumper. Also, it is hesitant from a stop. Something else I noticed is when slowing down to a stop from 30 or 40 mph, the rpm will dip to 450 right before stopping, then up to 650 then settle at 600. It did not throw any MIL codes and I am at a loss on where to start.

Any insight would be appreciated. I figure I'll start with cleaning the throttle body and MAF.

 

You might check and see if the cat's are plugged. If you don't have much coming out the tail pipe there's a problem. Just one idea. With the miles on it that would be a good place to start. It would be a good time to do your exhaust work HA!!!! Lot's of luck.
F96XLT

 

Original plugs? If so, at 111k, it might be time to replace them. You might do a search on "hesitation" or "acceleration" to see how others have solved their problem.

Best of luck

 

I replaced the plugs at around 100,000 miles with Motorcraft recommended by Ford.

 

Do you still have the original O2 sensors? If so then the front ones should be changed. Cleaning the MAF sensor is also a good idea. Cleaning the IAC should help with the idle problem.

Regards

Jean Marc Chartier

 

With all due respect Jean Marc I don't want to "throw money at it". If these items should be changed due to problems, wouldn't the PCM store codes?

 

I understand your reluctance at spending on parts for nothing.

The PCM is looking for O2 switching problems. The way the system is set up is that the O2 sensors see a lean condition and then the PCM over corrects by creating a rich condition then the O2 sees a rich condition and the PCM over corrects by setting an over lean condition. This constant switching from Lean to rich and back is monitored by the PCM and when the O2 sensor doesn't switch fast enough or at all, a code is set. Other factors, mechanical ones, such as injector problems or vacuum leak, can influence a lean or rich condition and if that occurs the PCM will pick up on that set a code becasue of that. It is not mentionned in the owner's manual but an old O2 sensor can actually cost you MPGs too. Have a look see at the Bosch site and read up on the replacement interval that they suggest. BTY Bosch makes the O2 sensors for Fords.

JMC

 

Don't forget the EGR ports. I have had to clean mine twice now and they were completely plugged both times. With the mileage you have it is a good to check them. Made a big difference in the throttle response, also gave me back two miles per gallon.

 

I thought the EGR ports were problematic on the 4.2L and 4.6L. Does the 5.4L have the same clogging issue?