I was on the highway going about 75 my car bucks like a bull. I see smoke. I pulled off the highway. Towed it home. Next day it sort of did the same thing. The d5 light was flashing. I took it around the block the next day and it shifts fine. I didn't put any transmission fluid in either.

 

I rather doubt your transmission is the issue.

 

What do you think it might be ?

 

Hard to tell; have you had the codes read?

 

No not yet. I'm going to do it today.

 

Blinking D5 means code store in transmission control module.. need a good scan tool to read it...

 

What color smoke?