The wandering coach

Weight distribution and tire pressure are the first two things I would check. If the front axle is too light, it will wander. Most coaches handle better with the front axle close to max. Tire pressure is also very important and a 4 wheel weight will tell you what pressure is best for your coach. Have it weighed fully loaded as you travel with full fuel, as much fresh water as you normally carry, and all passengers.
After this, then you need to look at alignment. A 4 wheel thrust angle alignment is more expensive but it insures that your rear axle is in exact alignment with the front axle.
After those things are check, then you are looking for worn/loose suspension components.
Start with the cheap things first before you spend any money on any accessories.

I have a 2010 Vista, and have noticed that it handles and tracks much better with full fuel and FW tanks. It likes the extra weight.

Add additional positive caster, even beyond the factory specifications.

theoldwizard1 is correct if all your steering components are in "like new" condition. You didn't indicate what chassis you have but some years of Ford with twin-beam front suspensions are particularly prone to this and need an aftermarket caster adjustment part to gain the additional caster required.

Thank you, yes it’s a Ford chassis with a v10 power plant.

I have no idea how much experience you have with driving large vehicles. If you have a reasonable amount of prior experience, then please feel free to disregard these suggestions and please don't take it as any sort of an insult.

It's certainly true that many motorhomes have less than ideal alignment and suspension setups from the factory, and getting these dialed in can produce a significant improvement in handling. (For the F53 chassis, also check out the "cheap handling fix" or CHF; search here for details.)

That said, it's also true that large, long-wheelbase vehicles by nature handle and behave differently than cars or pickup trucks. They take longer to respond to steering inputs, longer to accelerate, longer to slow down, and being wider one needs greater precision to stay in a proper lane position. It's easy to overcorrect if you're not careful. I find it helps a lot to intentionally keep my focus farther down the road, and only glance momentarily at the road just in front if needed. If you're focusing on the lane to close to the vehicle, you'll be chasing yourself to try to keep on track. I also found it helped a lot to think not so much of staying centered in the lane, but rather to imagine putting the driver's seat over the left third of the lane where it should be when the vehicle is centered. Since you're nowhere near the middle of the vehicle, side to side, you won't end up in the middle of the lane.

A good bit of it comes down to getting some practice.

All great advice. I drove flat beds and box trucks when I was a younger man. However that was at least 40 years ago.

DrewE, I’ll try that on the way home

I added 2* positive caster. That and a rear trac bar solved the wander. 35k miles later, all good.

Things to check (in order) -

First check your tire pressures. If you don't know how much the coach weighs then go by what Ford recommended on the incomplete vehicle sticker. For a 30' Sunstar not much over 80 psi is probably all that is needed. When I played with pressures once I hit around 87 psi cold (Ford recommended 80) the coach was difficult to hold in a lane.

Second your driving habits -
Try setting you eye focus several car lengths further down the road then you might in the daily driver. I've learn from getting back into motorcycles, and what I forgot, just how much where you are looking is where you are going to go.

Third have the alignment checked as mentioned regarding what others have posted regarding the caster and toe angles.

Fourth if your still having problems AND there is a lot of play in the steering wheel you can try tightening the steering gear box. For example - F53 steering gearbox adjustment RV. Small adjustments and you shouldn't need much more than a 90 degrees of a turn of the screw. Do 45 the test drive.

Fifth consider performing the Cheep Handling Fix - IVR2.com, Ford Forum, CHP.

Fifth check the rear sway bar bushings. The originals only last a few years past warranty.

Bolt on stuff -
Try a rear axle track bar then a front steering stabilizer. Each will run you about $400 so do the lower cost stuff first.

Cheap handling fix will likely do wonders. Did that on both my previous gassers and it was a remarkable improvement in handling, wander and truck push. best part - it's free and takes about 20 mins. As others have stated weighing and proper psi is also critical.

On edit - was thinking after this post, why is it called the cheap handling fix if it's free? Shouldn't it be the FHF?