whenever i start up my car from cold it will rev at about 1500rpm and have a weird vacuum sound and after about 30 secs the revs start to fluctuate like its misfiring then the vacuum noise will go the revs will drop off and will run fine after.

any ideas?

thanks

Your secondary air pump is coming apart. Have a look from under the bumper at the front of the engine underneath the alternator. The pump's a big cylinder thing with two black plastic hoses coming out of it up to the engine bay. Does it look like the two halves of it are held together or is there a gap between them?

The fix is to remove it and remove the rivits and replace them with nuts and bolts