Hesitant acceleration - Lambda?

I have been trying to figure out why my car feels a little hesitant when trying to pick up speed for a while now. It's only slightly noticeable but I can feel it. I changed the distributor, dizzy and leads and it's still there.

I had been suspecting the lambda sensor for a while so I decided to unplug it and go for a drive and it felt much better. Has anyone ever experienced anything like this or any lambda sensor issues that cause hesitant acceleration?

Having same issue just now with my 1ltr, disconnected the mass air flow metre (is MAF an abbreviation? Or something completely different) and it's fixed it, if not made it better, but get about 10mpg. Try taking the Mass air flow metre out and cleaning it, although you will need a rare 5 tooth torque to do it, which I had to order online, this solved mines but suppose yours could be completely different in which case I'm no help. But it's certainly something to check I guess.
i have a new engine ready to go In so I can survive for now