mdls400

ok..here is the problem with my 1992 LS400..i just relplaced the alternator and the power steering pump in it and was running fine after i was done..the next day i get in it to go to work and when i take off it starts to hesitate..when i start the car it idles fine and all but once it's put into gear you can feel a little hesitation and when you take off it hesitates..can somebody please help me figure this one out?? thanks..