THE Get up and go

I have not replaced my intake manifold gaskets(for the oil burining problem stgated in an old thread) yet, that is this weekends job... I had another question. my 94 gt has a steeda 19 cam in it with shorty headers(BBK).. I want to know why my car shifts at such a low rpm, it shifts when i go near 2000rpm, and sometimes around 1500rpm.. now it looks like the cam was put in by this kid i bought the car off of, but the timming is right(atleast when you check it with a timing gun,(is the timeing gun only good with the stock cam).
What i want to know is what could be making the car shift so low, and take for ever to get up and go...(my 97 mercury mountaineer w/a 5.0 gets up faster for an example..) Thanks