Our 1997 Grande Voyager is cutting out randomly. It usually starts up again if we get out of the car and rock it from side to side ?????

Recently we had our car in the garage as it would not run, it had a service, new pipes, leads etc, they also disconnected our gas conversion as they thought this was the problem.

But now one month on and £550 later we are in this situation as above???

Any advice would be greatly received, i'm a stay at home mum so not very mechanically minded lol.

Thanks again :)