1.6 vauxhall 8v,16v, single and multi point injection from 99/00 onwards. If it has the newer (no seperate idle control valve/sealed unit/fly-by-wire) throttle body and cutting out at junctions and bunny hopping with lack of power is occuring intermittently then this is the possible reason and cure;
When the engine is cold or the weather is cold then the ECU allows extra throttle via the (fly by wire) throttle stepper motor. On reaching normal operating temperature, and especially in warmer weather, then the ECU shuts the throttle butterfly completely and the idle relies on warm air coming from the smaller pipe connected to the cam cover. While all the pipes clog slightly, and are easy to remove and clean, the one area that is overlooked is the actual idle nozzle into the throttle itself.
REPAIR/FIX: 1:remove all pipes from throttle housing +clean them out.
2:remove throttle housing. REMOVE IT! (it can all be refitted with the existing gasket if you lightly seal both sides/faces with a non hardening gasket paste) clean the housing and all pipe junctions out.
THE IMPORTANT BIT 3:Take a small drill bit (1.5/2mm) and using pliers gently wind the bit through the tiny pipe hole under the butterfly (mine was completely solid and in the end i just drilled it out!) inserting the bit from the outside of the throttle housing and working inwards. This is the nozzle that connects to the pipe from the cam cover housing and is the smaller of the 2 pipes. (the other larger one goes to the air inlet). You will probably find that this tiny nozzle is blocked rock solid (like mine was), or just gunked up. Cleaning this nozzle is the clincher and is why the engine cannot idle. No need for ECU reading, replacing all the purge and EGR valves!!! if this doesnt work THEN you can safely go down the route of replacing valves and software etc...
any queries then you can email me on daell(at symbol)hotmail.co.uk - written on april 1st (after 12pm!) 2009.
ALIAS the 3rd, April 2009