Okay, I'm going to vent a little and hope for some suggestions and opinions. I bought my 07 FX4 in Jan with 95K. In the first month my passenger catalytic converter threw a CEL and the dealer replaced under warranty. After joining this site, I received numerous informative info about our trucks and ways to maintain them. In March I cleaned the MAF and TB, and afterwards I began hearing a hum around 3K RPMs. I was convinced I didn't replace something correctly, but come to find out it was the heat shield from the new cat converter. However, I did re-tighten everything around the intake and TB to be sure. So far, no more hum...however, while in park if I rev the truck up I can hear noticeable metal "clang" in the exhaust. Then in May I replaced the fuel filter not knowing when it was replaced last. In mid-August I noticed a rough idle while the A/C was on, nothing serious but could feel the vibration on the accelerator while in drive but stopped. In the last couple weeks, the idle has come and gone regardless if the A/C is on. Last night, for the first time the truck dropped below 500 RPMs at a red night and almost died, shuddered twice within a 10 second period before the light turned green. I've read about cleaning the IAC on our 5.4's and that's next on my list. The plugs get changed in December; I'm saving for a leveling kit, tool box, line-x, and 33" tires to all be put on with the plug change.

I'm not seeing any issues with loss of HP or MPG, I average between 16 and 17. The truck does have the infamous cam phaser tick, but it's only noise. The truck engine has a March 2007 build date, it's my understanding that's before the plug fix but after cam phaser. I've also used sea foam once in the tank and 1/3 in the vacuum lines. I saw little to no white smoke.

So...my question(s)

- The truck just rolled 103K, would the plugs affect any of my issues above in the past 10 months? A steady decline like that...
- Anyone who has addressed their MAF, TB, or intake tubing...have you had issues with a secure connection between the elbow and the air intake housing with the filter? I assume that was my "hum" and I used electrical tape to seal it.
- Fuel filter, would this cause any of idling issues or they all related to air flow? I used a Purlator (sp) from Auto Zone.
- The TB and MAF we so-so dirty when I cleaned them, but I've seen negative results with other issues showing up.
- I've had the oil changed twice; once at purchase by Ford and then at 100K by local shop. Change at local shop used synthetic blend for the first time in the truck.

Am I doing something wrong or have I just bought a truck at the exact time where these symptoms occur, around the 100K mark I really hope that I can respond to this thread in December that my issues are ALL resolved and the truck sits level with 33's. If anyone reads something obvious, had similar issues, or just want to chime in...please do. I love this truck, it's stressed me our at times but at the end of the day it gets me from A to B...I just want to keep this truck a long time.

 

100K it's due for the plugs...could cause everything you talked about...BTW your truck came with synthetic blend in it when new.

 

check plugs first, then just fir *****s and giggles unplug your maf sensor to reset the intake settings to factory.. if it still bogs then its more than likely the plugs or the iac

 

Plugs are being replaced and I'm getting a fuel injection flush soon, I'll update about the rough idle, so far that's the only issue.