iroc29

i have a 87 iroc z28 with 45k on it 305 tpi it sat for many years and i have poored money in it im finaly down to one code, its code 41!!!!! i have put in a new ecm but used the chip or prom or memcal or what ever its called FROM THE OLD ONE lol< car idels high, hard to start and blows a kinda white smoke when you first start it, it sputers to life but some times fires right up!!! it idels up and down, and some times on the high way the check engine lite will turn off and come back on when you hit the gas, PLEASE HELP