I have a 1990 560 SEL and the plastic vacuum hoses and rubber tubing are very brittle. I have replaced most. How dificult is it to change out the fule injector holders and nozzle guides. The engine has a rough idle. Fule pressure good and I have changed out EHA because of leak indication. It help but still rough idle. I removed the injectors and in a down hold inspection I noticed the tip of the holder looks broken but still attached. It looks like it could interfear with spray pattern. It's on #8 cylinder

Any comments Please.

Thanks, H. O. Tyler
90 560 SEL 130 K
85 300 SD 62 K
83 240 D 260 K