knocking after inlet manifold removal

[bower]

hi was after a bit of advice, on the weekend i removed the manifold and gave the valves a good clean, put it all back together and cleared all codes  
set off to work on tuesday and started to hear a loud knocking coming from the front of the car, it happens when i let the revs off and just coast, whether its in gear or out of gear and it seems to follow the wheel speed and i can feel the knocking through the pedals, now it could be a coincidence as the manifold doesnt have any moving parts but just my luck its started as soon as i work on it so im paranoid its something ive induced? any ideas of what to look at anyone?

[doylebros]

Not that missing socket rattling about?

[bower]

stopped doing it now, dont know what it was

[biffobear]

Maybe a lump of carbon rattling off a piston, and has now been broken up