First, check fluid level. If that's ok, then likely the power steering pump is going out. I'd have a Ford guy check it out. Doesn't have to be an RV guy, but someone that can listen and give you a first person diagnosis.
2006 Damon Daybreak 3276 35'with 5 Star Tuner. 3 200 Amp Lithium batteries and 2000 watt PSW inverter/charger. 2013 Elantra on a Master Tow dolly.