Hey guys!

My 1988 740 GLE (NO TURBO) has a bit of a problem. You see when i drive on the highway, it tends to slightly fish tail from left to right from the rear of the car. When ever i change lanes, it seems as though the rear is delayed with catching up with the front-end, hence the fish tail motions. Also when i accelerate on a turn, my steering wheel does not return as it should, i have to sort of help it along. The wheel is not hard to turn either, and the steering itself is not really stiff, leaving me to wonder what the heck it might be? The u-joint coupler in between the shaft has been lubricated several times, and does not seem to indicate any problems. Also the steering rack is not leaking and or appear to be stiff. The tie-rods and or ball joints seem to be ok, but i don't know? When i am on the highway, the front-end does not clunk, shudder, and or wobble whatsovever. The car has 179,000 miles on it right now. Does anyone know what parts i should get and or more important what is the problem with my vehicle? I love the car,and purchase nothing but the best for it (synthetic fluids/strict maintenace etc). I even checked my P.S fluid condition/level,tires,and drive belts. Should i just replace the belt, even though it is not slipping and or showing signs of dry rot? Might it be the PS pump? Please help! All of your responses/help would be greatly appreciated! Thanks in Advance