97 cougar engine and 95 tbird ecu

Hello I am about ready to scrap the engine in my 95 thunderbird 4.6L because I can't seem to get it to run right at all. Since it was put in it has always had a misfire. I have done plugs/wires all filters oils check gas to make sure it wasn't bad have put it on the computer time and time again and it smokes heavily (white oil smoke). I am thinking it is either something internal and I can get a new rebuild engine for 95 thunderbird at a yard near buy but before I did I thought I might ask. We blew the first engine because the oil was never changed and 4.6L is gone at 100,000 so we had another put in it which we believe came from a 97 cougar. So I am wondering if the ECU might be messing me up and I just need to get a 97 cougars ecu. A 50 dollar ecu would be lot cheaper than 600 dollar engine. Thank for you time and any help.

So I am wondering if the ECU might be messing me up and I just need to get a 97 cougars ecu.

Per your signature you have a DOHC engine.
You will need an ECU from a DOHC, automatic transmission, vehicle or
have your current ECU reprogrammed.

thank you very much than I shall go get a new ecu and see if that works. I just wanted to see what an expert said I have learned a lot but all these computer things mess me up. Once again thanks for your help.