Code

[mgm6397]

What could be the most likely cause of a Ford PO174 code thank you

[gadget73]

On what?

[EaOutlaw1969]

seems to be a lean code ( check for broken or disconnected vacuum lines ) but since I do not know what your working on this is the extent of any help I can offer.

[sly]

Here's a nice little write-up.
https://www.aa1car.com/library/ford_lean_codes.htm

That said... could be a roached sensor, cracked exhaust manifold, loose manifold, loose downpipe, loose EGR pipe... Lots of stuff coming loose could cause that.