Here we have a 2003 ford f150 5.4 216k miles. Runs very well, very reponsive--except for a slight vibration in idle. Enough to feel it in the seat. No codes, or anything. Should I be alarmed? What are some things to check for?

 

Is it a constant vibration or erratic vibration?

 

A constant steady vibration...

 

Just a vibration, a slight miss...nothing serious

 

You should be, a worn mount will wear out other mount (engine, tranny or body) then it wear out your radiator & coolant hoses.

 

Did a complete radiator flush a couple months ago, all coolant hoses were visually inspected. What else could be a possible cause?

 

Engine Mount & Transmission Mount are OK?

 

Well, have you tuned it up ....ever?
Plugs, coils, new balanced injectors, fuel filter,new motorcraft pcv valve, egr valve
Check for pcv tubing or other vac leak

But instead of spending $700 chasing a non-problem on a truck with 216000 miles, you might just drive it.

 

Haven't checked yet. If that's the case I might as well do a rebuild.

 

No, the most I have done is replace the pcv valve. I had a code of PO171. Cleared it by replacing all pcv piping. That's all I've done. Maybe I will give the MAF and throttle body a cleansing, and replace the fuel filter for a start. You recon?