Hi,

I am am new to the portal. I have searched the threads and saw several posts along similar lines to my issue but did not see any where the problem was found and resolved. Most were older posts. I have a 2006 F-150 Lariat 4 x 4 5.4l 3V. Here is what I am experiencing and what I have done:

When I first start up and the engine is idling at @1,100 rpm the engine runs really rough. Once it drops down to about 800 or 900 rpm it runs fine. While driving I experience the same thing when I am at about 1,100 rpm. Shakes and vibrates when I start to accelerate at that rpm. Here is what has been done fairly recently besides normal maintenance:

1. Spark plugs were replaced by dealer at about 107,000 miles
2. All COP’s replaces at about 110,000 (about 2 weeks ago)
3. All fuel injectors replaced about a week ago
4. MAF cleaned with MAF cleaner about a week ago

All parts swapped out were Motorcraft OEM.

Thought it might be the CAT or O2 sensors but everything looked ok when looking at live data on the scan tool. I am not seeing any codes whatsoever. No pending, nothing. I know this is not normal because it never did this before. Any ideas?

Thanks in advance!

 

Check your FPDM for corrosion and cracks. It's under the spare tire, and can be done rather easily.

 

It might help to clean the throttle body, especially if it has never been cleaned.

 

Cleaned the Throttle Body today. No change. Will try the FPDM tomorrow.