Well like you say...

Drain the torque converter (consider doing the transmission oil cooler lines too) replace the filter and check for debris. Drive it and see how you go. As we don't have smelly-net (thankfully!) I'd take a sample of oil to someone who knows, to get a second opinion, if you are unsure about the burnt smell.

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1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!