Toyota Repair: transmition blues on a 1996 tacoma truck, tacoma toyota, torque converter

Question
Mr Expert.
I opened the hood of my 1996 tacoma Toyota (112000miles)
and noticed the cable to my transmission was "loose"
The repair resulted with improved gear changing,however since then
the oil is always much darker(I was told it should always be red)
almost black.
What is going on?
Maybe other Tacoma owners are facing the same trouble.
thank you

Answer
When was the last time the transmission fluid was changed? On this model it should be changed every 30,000 miles, if it's shifting ok then I would recommend changing the fluid as soon as possible or even have the transmission flushed with a machine to get all of the old atf out including the torque converter.