Hey Noreen,
We're used to those warning stickers here in California, but if you're from other climes, they can be a little frightening when you first see them. Most if not all of the synthetic materials used in the interior of cars, motorhomes and houses will release gasses when they are new. That's what you are smelling when you have that 'new car' or 'fresh carpet' or 'fresh paint' odor. But since your car, motorhome and house are not completely sealed - and you aren't breathing only those gasses - the odors are relatively safe for healthy humans - unless of course you are alergic or sensitive to those chemicals.
Quite frankly, I'm more concerned about molds than I am about any 'toxic gasses' coming off the foam or carpet. A good cleaning with Tea-Tree Oil is a good natural way to keep the molds at bay. Also, I pull the foams out and set them up on edge - with the roof vent cracked - while The Beast is not being used - and I keep the curtains closed and the drawers/doors slightly open. This prevents molds from taking hold and growing.
Should you replace your foam? Well, that depends. Unzip the coverings and take a look at the raw foam. At the age of your MH, I'd expect to see some yellowing. If the surface of the foam is hard and crunchy, or if it is just foul, I'd look for new foam. If it is stained from a bottle of spilled wine, or if it is musty smelling, I'd give it a good cleaning with a good quality carpet/upholstery hot-water cleaner/extractor - I would use some tea-tree oil as the 'soap' as it is a natural mold killer. Leave it out in the sunshine for a couple of days - UV tends to kill mold spores too. You could also encapsulate the foam - in other words, wrap it in a sheet of plastic - if you wanted to save a stained piece.
Take a look at the upholstery - If it feels bad, or if it smells musty, you could try to clean it with the Tea-Tree oil. Upholstery material is not cheap - but it is heavy and will last a long time. But mold is not good for either the fabric or you!
The carpet and padding are probably goners - it's been absorbing everybody's muddy footprints for almost 15 years - and pet stuff - and odors... Carpet is cheap, and some people on this site have installed wood laminate flooring - which looks really cool and is really easy to sweep and mop, and doesn't accumulate dirt.
Don't forget to hit the hard surfaces with a diluted mixture of Tea-Tree oil too!!! Molds can grow anywhere - and since the windows tend to leak and/or sweat, it won't hurt to wipe everything down on a regular basis!
So, don't let the California stickers make you paranoid. Give your MH a good scrub, dry her out, load her up and take off for a weekend or two!!!
Lance
"I've got nowhere to go, and all day to get there!"
(BTW, I prefer dark beers, but if you have a local microbrew - 'Bring it on' and grab a mug!!)