the nova keeps giving me a headache

i have not had use of my car which i rely on for work for weeks now. When im driving the car seems to keep cutting out then wont idle after working just fine ive tried so many things,it seems to me the plugs are recieving an intermitant spark sometimes it firing on all 4 then nothing then back on all 4 its not the coilpack i know,ive replaced the cranksensor.what tells the D.I.S pack to spark,the ecu determined by what the crank sensor tells it??? shall i try a new ecu? its a C14se by the way thanks all