hello boys & girls, i have a random running fault with my saff cossie.

its been running spot on for ages & last sunday i gave it large it 1st & quickshifted it into 2nd & BANG!!!!!!!!!!!!!

car rolled to a stop & the result was a broken diff but....................

when the car rolled to a stop i noticed it was running rough asif it was on 3 cylinders

car was towed to lock up & new diff fitted today, started car uo for 1st time since & its running rough still.

i tried another set of plugs in it & no joy


heres what it does:

runs rough on idle but assoon as throttle touched its mint & to drive it you wouldnt know there was a fault till its back on idel again.

when car runing rough on idle if u gove it 2-3 large revs it will the idel fine
or
if driving it & give it large then pull up it will idel fine

i did notice the engine does have a noisey tappet now & was thinking it could be that collapsed on idel (not enough oil pressure for it) causeing the valve not to be fully open when when revved & oil prerssure rises its all good

any other idears??????????????????

whn u pull a ht lead off 1 at a time the all make a differnce & its getting fuel & spark to all 4 cylinders

cheers