I had a similar issue with a GM car. I gutted the interior and used my hot water pressure washer in the inside shell. followed that up with a coat of rustoleum flat back on the inside shell. Brushed it on. All the plastic garnish moldings have been redyed. The dash can be an issue also as they pee everywhere in and on top of everything. Upholstry is all new. I think i got it but it was a lot of work.and cost