[N*Caddy]

Just changed the spark plugs and wiring (everything ACDELCO). The spark plugs were looking fine (no cracked insulation, yes some carbon deposits but I have seen worst). The spark plug wire set looks like being original (if is the one with cylinder numbers printed on). Strange is that the new cables (bought from rockauto.com) don’t have the numbers (also some small length variations). Anyway with this occasion I discovered another plastic fuel line cracked (the one between cylinder 1 and 3). I had hard time to see the cracks, the gas smell was pretty noticeable in the last week, some fuel leaks when idling, and the most obvious proof was the gas dripping from the rail after removing the beauty cover. The cracks are plenty and minute and they develop along the rail. You can only see the cracks if you slightly bend the rail. Now is clear I GOT to replace the darm plastic things with the stainless steel rail (right now I have 3 hoses and that’s a Mickey Mouse solution).
Question for those who replaced the rails: The stainless steel kit from rockauto.com (ACDELCO Part # 12499784 ) is ALL I need, do I need to buy some additional parts or not? My concern is the connection between the rail and the injectors. Aaa … and one more thing, how do you remove the plastic things on top of the injectors, do I need a special tool or something? I’ve notice that they appear to be fixed in place by a metal tab. I tried to remove the tab but after some attempts I aborted (I was afraid to crack the top plastic part).
As for the tune up, in the 50 km or so driven after, I had no more shaky idle (maybe a slight roughness witch I believe is due to the hoses elasticity, you know, the Mickey Mouse solution) but other than that is a 98% improvement. Also the misfires (more and more frequent lately) are gone (so far). But then again, one year ago when I replaced first time the spark plugs, I had two weeks or so of perfect idle and gradually the problems came back. My question is … will I finally close this thread after I replace the fuel line?