my car only idles at about 250revs and until warmed up a little bit wont run unless u hold your foot on accelerator to where it should idle. i fitted new idle speed control valve but this didnt cure anything. no fault codes are bein shown. garage said the ecu is probably fooked but i cant imagine that be the reason. any ideas? prob one of the sensors like maf or summit yea?

 

TRY DICONECTING THE AIR FLOW SENSOR AND LAMBDA SENSOR M8

 

sounds like an air problem.
if its not the idle valve then it could be the maf faulty?
air leak?
air leaks can be anywhere from the airbox to the head face itsself.
when cold engines run rich, if its got air leak then it will run weak.