Car loses power whilst driving and stalls occasionally.

Car starts fine, and at time drives fine. However sometimes when accelerating the car slows down or pulls back (as if i've taken my foot off the accelerator), and I need to baby it a bit and tap the accelerator a few times or wait it out before it becomes good again and continues driving normally. As a result of this it often stalls.

This usually happens at lower speeds, and when the car has just been turned on. It seems to be a lot less noticeable once i've been driving for a while, and once I'm driving at higher speeds.

I've replaced the fuel filter.

Any advice would be great.

Thanks