Please help.

My 2005 Altima took a while to start this morning. It kept turning over but never hitting. I had to manually give it gas in order to get it to start. It's done this before. Once is gets going it runs fine.

clean the throttle plate really good. Its dirty

Your fuel pump is bleeding off pressure back into the tank. You can change the whole pump, or there is a check valve you can change (located in fuel pump assy.) .