The transmission in you car should be a 722.4, since you serviced the transmission; other possibilities are a sticking engagement valve or torque converter charge valve in the valve body, leaking drum rings, internal. If you what to do a simple test just start the car when cold preferably over night , do not engage any gear and immediately check the transmission fluid level in park; if the levels reads very high the transmission has a internal torque converter drain back problem which will cause a delay engagement