Automatic box

I have a 1998 Mitsubishi Lancer GLXI 1.3 automatic, and I'm having the following problem: when shifting from Park (P) to Drive (D) and accelerating, it doesn't engage; the car doesn't move. I have to shift down to 3 and then into Drive (D) for it to start moving. Also, above 80 km/h, the RPMs climb as if it needs to shift gears; in fact, at 110 km/h, the RPMs reach 4500. Thank you in advance.