No horsepower on Low RPM's 91 CRX DX HELP!!!!!!!!!

At low RPM's like anything under 2500-2700 the car just putts along then it takes off..........like snot when the RPM's start to get higher.

Its a ***** for taking off as the RPM's have to be at about 3000 or the car just Lugs down to a crawl.

I just put this used engine in about 4 months ago and it has about 70,000 miles on it.

The compression was good and everything when I got it. But this No power thing, and high reving take off is getting to be a pain.

Does anyone know why may car needs to be around 2700 rpms to have any power.

If I have it around 2200 RPM's I can floor it and it still just slowly (and I mean slowly climbs) It takes about 5 seconds to get to 2700 to 3000 (and thats with it floored).

What could this loss of power be?