As mentioned, check tire pressures to make sure that they are correct according to your weight. Second, get it to a reputable heavy truck shop that knows suspensions and have them check it out and possibly align the front end if it can be.
Mine had/has what I consider loose steering, but nothing unmanageable. After taking it to a truck shop that specializes in alignments, I was told that my king pins were worn...not to the point of a safety issue, but worn enough that it would not hold an alignment. After pricing the replacement of them, (close to $2K), I decided to try pumping the grease zerks full and see what happens. Well, when they are full of grease, it drives like it should. So, as long as I can, I will pump them full every couple months and go about my business.
Of course, there are other things you can add...steering stabilizer, rear track bar, etc. But if your tire pressures and alignment is not correct, or if you have worn components...you won't be satisfied.
1999 Holiday Rambler Endeavor, 36' Gasser
Triton V10, Ford F53 Chassis
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