I need to adjust or replace the throttle cable, due to feedback through the accelerator after about 4k revs.

Don't have a clue how to though, but would like to learn how to do these things. Is there a guide anywhere i could use, preferably with pics?

Also alot of rattling at idle and low acceleration from under the bonnet which after abit of research appears to be the cat heatshield. Does this sound about right? I think it's this as my local ford garage recently ripped out abit of the heat shield from above the exhaust and that improved thrattle, but didn't get rid. Any way i could go about fixing this?

Thanks!