sound peeps, im havin a few problems wiv my rs turbo cabbie,when im driving along its all good but when i come to slow down the revs go right down an cuts out,an when it comes on boost it judders realy bad,i checked the timing and all is good,no boost leaks as far as i know,but i did take the spark plugs out and they are all white wot does this mean! its not long bin rebuilt an its not chipped, an running standard boost.any ideas because summer is round the corner and its gota be sorted thanx craig