Lower gears and still slugish.

There are a lot of people here that can help but with the limited info you gave it would all be guess work. that said I'm guessing you have a bigger cam and 4bbl and maybe headers. most likely first thing you need to do is get initial timing some where in the 18-20* BTDC then need to limit total timing to 34-36*. Another thing to check is if you are actually taking off in 2nd. Manually shift into low run it up to around 25-30mph then manually shift to 2nd (did it shift} then run it up to 50-60 and manually shift to drive and make sure it shifts again. if you only get one gear its possible you are leaving in second.