I spoke with a mechanic and he said that my "rear crank case plate" needs to be replaced to stop the rough idle that I am experiencing. I don't know what he is talking about. I have the new engine in it and I also replaced the O2 sensors because the check engine light came on and said that the O2 sensors were faulty. After I replaced them the problem continued and I had smoke coming out of the tail pipe. The mechanic said that it is fairly common problem. What I want to know is what should I replace to get it to work right. Any comments would be appreciated beforeI take in to that mechanic for a $400 repair he said it would cost me.