Car stuttering losing power in 2nd till I give it more acceleration.

I recently had a Timing Belt Snap and got it repaired,

my car has been playing up last few days, , I could hear a clinking sound and when I was taking of every so often there was like a small back fire noise, if I was in to high a gear she would really stutter,

this was particulary obviously if I was in a road were there was quite a lot of ramps near each other

i got the exhaust checked he said there was nothing wrong with it had full comporession

but what he did notice was that an arm had come out of this I think its vacumn maybe someone here can tell me or advise what might it be