Rpm concern

Hi,I have a 92 SVX,which I have just changed the tranny from a wrecked SVX with 40k original miles checked at the DMV.
To avoid all problems,related to tranny I installed an external cooler the B&M 70268 and I installed the B&M proper tranny gauge to control the temperature,besides that I am using ATF Mobil synthetic fluid,and I also installed the shift kit from www.smallcar.com which helps the transmission shifts more firmly through manifold pressure,but I am having a problem that I hope somebody can help me to solve,the first shift comes up when the car gets to 4000 or almost 4500 rpm,if I release the foot from the pedal at about 2000 or 2500 rpm it shifts to second,but If I step on the gas normally it won't shift at less than 4000 rpm,the rest of the shifts are normal,but it is the first one I am concerned.
The engine runs nice and the former tranny owner told me his car did not do so wuth that tranny.If it helps,I do not have an extra filter,and the temperature stays around 170 degrees.