Need Advice with Rough Idle Near-Shut-Off

[Leigh9]

I have a 2005 8 cyl RWD with 150k miles on it. It has been well maintained and is in generally good shape. Recently (last two weeks, maybe?) I have noticed a soft rattling noise while idling. Then yesterday it shook and nearly died while waiting in line at a drive-thru. The only thing that stopped it was flipping it into neutral and laying on the gas a bit. The rattling noise is still there, but I have had no issues with it feeling rough or nearly shutting down. The check engine light is not on, and did not come on during the drive-thru incident. For all intents and purposes, it is business as usual except for the addition of the soft rattling sound while idle. As a side note, the rattling noise stops if I go into neutral, park, or put on the gas.

The most competent mechanic in town will not hesitate to recommend unnecessary repairs to people who do not know better. My other option would be to drive more than an hour to a mechanic in a bigger city, which I worry about since there is at least a remote chance that I will break down along the way. Either way, I am concerned that the problem will not be obvious enough yet for the mechanics to diagnose (one of those "I swear I wasn't just imagining it" things).

Does this sound familiar to anyone? Any educated guesses on potential causes? Are the chances of a breakdown imminent enough for me to risk the local mechanic, or would you recommend trekking to town?

Any thoughts or ideas you have would be much appreciated!

 

[John Stephan]

Disconnect the VCT solenoids, one at the front of each valve cover and see if the problem goes away. It will trigger a check engine light but puts the variable valve timing into a default strategy. If it does help, you probably need to clean or replace the VCT solenoids as they can get clogged by debris.

Reaching 150k is a milestone for a full timing overhaul. Better to get that done sooner than later as later can cost thousands more.

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[John Stephan]

Check out Fordtechmakuloco channel on YouTube. He has great how-to videos on the Ford 5.4L 3V engine.

This video should help with your problem.

Here is more info about the solenoids.

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