Car starts most of the time?

Hey everybody, I have a question about my 1996 Oldsmobile Ninety-Eight. Okay so I just had a new starter put in, and it still wont start occasionally. I turned the ignition and the engine caught but was kind of puttering, and sometimes if I gas it, it'll help catch and I can drive, but other times it'll just turn back off. It seems to happen when I stop and start the engine a lot in one day. If anyone could send some suggestions, it'd be greatly appreciated!