I had code p0340 pop up so I changed the CMP and both CKP's. Engine still idles rough though when I get it up to speed it seems to go away. Reading the forums I see that it is supposed to have a "relearn" procedure performed. I take it to a Chevy dealer (mistake) he tells me there is no relearn procedure for a 97. Is this true? If no relearn procedure how hard is it to time the N*'s?