1998 Vauxhall Vectra car jumping when dropping down in gears

when the car is cold she runs great but when shes warm she starts missing until i pick up speed its mainly 1,2,3,4 gears now a light comes on the dash board once the car temp hits half way, mostly when you take your foot off the accelerator, has anyone had the same problem as this is doing my nut in.
thanks.
I've just changed the spark plugs, ignition leads new seals in rocker cover, new oil filter,complete oil change, new air filter,cleaned out the carb with carb cleaner. i gotta new petrol filter to put on. Took it to my local garage, they hooked up there machine to the ECU that said idle control valve, MAP sensor, egr, the guy just said let me try something so he reset the ECU then started the engine, took another reading and all was cleared no probs showing, AAArrrrrggg please help.