car wants to stall while driving and sometimes has a hard time starting

I have a 93 Nissan Sentra 4 cylinder I had a new starter put in. sometimes when I try to starting  the car won t turn over after several try's it finally starts. also while driving you can feel it hesitating to go and sometimes when sitting in idle for instance at a light and I press on the gas it stalls or acts like it wants to. if you can reply back to me at jseashore4@aol.com thank you