1984 Dodge 600 Turbo

[smiley2004]

We restored our 1984 Dodge 600 2.2 Turbo. The transmission was completely rebuilt by a certified transmission shop last year.
The problem we are having that when we drive it it is sluggish as it shifts into 2nd and it never gets up to a normal speed. It is an automatic.
Could there be a problem with the torque converter or is it just the transmission we need to focus on?