Engine management light has come on?

I have just had a new clutch on my car, new alternatitor and thermostat switch, battery etc my car feels like it has no power and struggles to get to 30 and feels like it's going to cut out when going down the bypass doing 70mph and is really jumpy. Have also changed spark plugs and has made no difference.

Help !!! not sure what it can be. having serious problems with my KA 1.6