Ford Repair: Transmission, 1993 mercury tracer, mercury tracer

Question
Hi Eric,
I own a 1993 Mercury Tracer,4 cyl,1.9L.Milage-136,000.
I bought the car 2 months ago and has been trouble free up until now.It seems sometimes when I am in the 45 to 55 mph range,the car "shudders"for a few minutes ,then it is ok.
It only does this in the 45 to 55 mph range.
However it does not seem to slip.
Someone told me this means it's time for the transmission to be serviced.I heard if I get the fluid and filter changed this could solve the problem.Is that correct?
I do not know if and when the transmission was previously serviced,but the fluid looks brown but does not smell burnt.Also, the car is not leaking transmission fluid and the level is full.
And the car has never overheated since I have owned it.The transmission is automatic,by the way.
What do you think? Thank you for your help.

Answer
Hello and thanks for the question...I'll try to help.
What it sounds like that is happenning is called torque converter shudder. I would have the transmission serviced and flushed. If this does not correct the problem, you might need to replace the torque converter to resolve it.
Hope this helps,
Erik