car keeps juddering corsa 1 litre 2001 ?

when i slow down in my car it keeps juddering as if i am about to run out of petrol, my car had oil and water and petrol as i filled up last night thinking that i was running out of petrol but it is still doing it now ... when i drive fast it seems to be ok its when i decide to slow down or come to a stop it starts juddering and like purring sound before it stops... i have had a few problems with this car and hope this is a simple fix