Jeff gives good advice.
If your Southwind has the Chevy chassis (P30, P32, etc.), check the air bags in the front suspension - it's not unusual for them to be leaking in older rigs. Low or no pressure in the air bags will make handling very poor. Pressure should be in the 75-90 psi range. If your rig has a Chevy engine, it is almost surely on a chassis with air bags. ANothe rproblem in this chassis is the steering mechanism - a component called a bell crank is poorly designed and manufacturered and gives slopy steering. Replace it with a Henderson Super Steer Bell Crank, available from Camping Wrld or direct from Henderson Line Up (http://www.hendersonslineup.com/)
Sway is a common problem in older motorhomes - the chassis weren't really up to the job of handling the big boxes on top. Anti-sway bars help and a company called IPD is the foremost supplier. Get one or upgrade the one already there (if any).
If you have laf springs in the front rather than air bags, you will want a device called a panhard rod. I recommend the Davis Tru-Trak bar, available from Camping World or from Henderson's or direct from Eric Davis at Eric's RV (http://www.ericsrv.com/). Easy to install yourself if you can swing a wrench.
If you would post information about your rig's chassis type, length and GVWR rating, we can probably fine tune the advice for you.