put car into local diagnostics centre which came up with no fault codes. upon further investigation they found that no's 1 and 4 spark plugs were arching. all 4 replaced and all was well.......... until this morning when started up having not used it all weekend back to bad running although it now idles perfectly. the problem seems to be when its under load, if you feather the throttle its fine, as soon as you give it too much throttle it hesitates and judders. also engine light was flashing and then gone out again!! dont cars do your head in?
would agree with your unmetered air solution so if problem re-accures with idling that will be my first port of call.
Many thanks steve