Yo! If your transmission hasn't failed completely yet, get it to a competent shop and have the transmission fluid replaced - all of it. There is a machine for that project that gets all the bad stuff out. Don't let them just remove the transmission pan and replace what falls out. You need to get all of the bad stuff out.

I bought a used 93 850GLT. Tranny fluid smelled a bit burnt. I scheduled a replacement, but the second and third gear clutch packs went puff before I got it in. $2600+ to repair. Symptoms were high rpm and no speed, meaning the transmission was slipping - big time.

Tranny fluid condition is a lot more important in late model vehicles, due to what I consider under-engineering. I'm from the 1960's Mopar musclecar era where the drive train was over-engineered and couldn't be broken. I used to build and race Mopars on the drag strip. Modern vehicles are engineered for light weight. Add complexity to that, and maintenance intervals become more important.

Even if the transmission fluid is a cheerful red color and has no burnt smell, change it every 30,000 miles. You won't regret it.