I've just fitted some jom coilovers to my mk1.5 focus the brakes were spot on before hand and since the coilovers have been fitted the peddal feels like it is just going to the floor when I'm stopping, but today I heard I slight hissing from around the brake servo has any one else had this problem before or have any ideas would be a great help

First thing I'd be doing is removing the wheels again and checking for fluid leaks, as when fitting these you were working in close proximity to the brake hoses in the wheel arches, may be possible that you have caught one that could have been old and brittle and its sprung a leak. Only plausable reason for your problem really. Unless it has actually developed an unrelated problem at the same time.... Check the resovoir for fluid loss also.

Their is no fluid leaks that was the first thing I checked and the fluid level is fine hasn't dropped at all

was it a hiss or a metal on metal grind? could be an unrelated problem such as pad wear/contamination

It's a hissing noise and I cleaned all the brakes off as I finished the coilovers so don't think it's contamination. I think it may be something to do with the vacume pipe to the throttle body because I can pump the pedal and it comes back up but when I start driving looses peddal again

Jack it up take wheels off and check for play in front wheels, if a front bearing is loose or has play as it moves it can push the pistons back giving you a long travel peddle but will pump up on the spot, if you pump it back up whilst still does the peddle stay hard until you move, did you remove the disks if so remove again clean surfaces and refit and retry.

think you need to narrow this down

with engine off, pump the pedal till its at its highest/hardest, then hold pedal down...if pedal sinks then you have a fluid loss somewhere...this could include an internal leakage such as master cylinder or...and this might be relevent..brake hose...

the internals of the brake hose can break down allowing fluid into the external part of the hose, release the brake and fluid returns to the inner leaving no signs...so get someone to operate the pedal whilst you keep a close eye for any bulging of the hoses.

if pedal stays solid, then release, leave for a minute and try again, if you find you can still pump the pedal up, you have air in system problem.

if this is ok, then with pedal held down, start the engine, pedal should sink a little as servo kicks in, but shouldnt sink too far..if it sinks lower than normal then worth bleeding the system before anything else.

if this is ok, then drive the car, if this causes the pedal to sink lower, then look for play in wheels as suggested in other post.

the hissing most probably coming from servo system, in theory, this shouldnt affect the pedal height but in practice it can...not sure on focus, but check the seal at rear of servo where pedal goes in, could be this seal that is leaking (if so, normally the hiss stops when pedal is pressed, but check anyway if this isnt the case)..failing that check all other hoses/connections to servo system, plus check for any other leaks around manifold as this could reduce the vacuum available for servo if leak is elsewhere.