Everything has been working fine since... I'm baffled.

 

Well I have seen some problems with fdml causing odd idle issues Also a easy forgotten maintenance piece is the fuel filter. Another place to look

 

Thanks for the advice. I'm not sure what FDML is but I will add the fuel filter to my list.

 

Low idle can be attributed to a dirty throttle body, amongst other things. I'm not a believer in tossing parts and solutions to a symtom, as it's costly. Eventually you do correct the problem, but at a cost.

Many have simply removed the throttle body (easily done by removing the air filter tube from the throttle body), the side wiring harness, then the bolts that hold it onto the intake runner. Get a can of throttle body cleaner (do not use gas or choke cleaner, as the throttle body plates have a coating on them that gas and choke cleaner will remove). Spray the backside of the throttle plate, the bore and front side of the plate, then re-install. This has corrected many low idle/stalling conditions for folks on this site. This is a cheap fix if it's attributed to a dirty throttle body.

If you need pics of a simple removal of the throttle body, take a look at this thread:

https://www.f150forum.com/f72/how-cl...ody-maf-75006/

 

I was wondering if there is a gasket that goes on before installing the throttle body back on engine. Or does it just go back on?

 

Their should be a gasket their

 

Cool thanks!

 

No problem

 

x2, and IMO I don't think you have a plug issue although changing them now would be a must for me. I have had a plug go bad in the no. 8 cylinder and I knew when it happened. If the truck has not acted up recently I would rule out a plug issue.

 

Thanks for all the advice. I will put the work in and let you know how it went. I will be towing again in 3 weeks for 4 1/2 hours each way and should know if it all worked. I plan on doing the TB, plugs, wires and air flow sensor.