Could be lots of things, but try this one first: Disconnect airflow meter (the round thing atattched to the rear of the air filter box). Pull the plug off (5-pin) and take for a test drive. If the van is actually faster with it off then change the airflow meter. By the way the engine management light will come on when you do this, not to worry it will clear down when plug is back on and engine re-started. Very common problem in our van workshops. Two types available OEM quality and cheap & nasty GSF type (£45.00 as opposed to £75). Cheap ones often fail very soon after fitting, don't waste your time with these ones.
Expert Van Services, June 2011
