Hello there first time user of this form so forgive me if this is the wrong section. I have a 1984 300 turbo diesel it has 385 k in mileage. Over a month ago the transmission started slipping and flaring between gears it would go away eventually as I was driving on the road.

I thought so myself it was probably time to do some work with the transmission such as changing the fluid the fuel filter and the secondary filter. I don't know the full history about the car I bought the car from third owner I think. I looked on the Carfax and it said the transmission fluid was changed 1 year ago that's as far as I know. Anyways today I got the transmission fluid changed I used full synthetic this one Valvoline™ MaxLife™ Multi-Vehicle Automatic Transmission Fluid - 1 Gallon

http://www.walmart.com/ip/Valvoline-MaxLife-Multi-Vehicle-Automatic-Transmission-Fluid-1-Gallon/15125768

When I took it out on the road today it was flaring even more than it was before I had the transmission fluid changed. Can someone tell me why it could be doing this? I am really stumped. thank you so much I really appreciate it