One question. If I am cloning a drive which I am having trouble with won't that just preserve all the problems to a new disk image?
If you are cloning or trying to clone damaged/corrupt files, then yes, the clone will also contain them. If the problems you're having with the old drive are caused by a damaged directory on that drive, there may be some damaged files on it that you haven't discovered (because you haven't opened them since they were damaged). Directory problems on the drive may even prevent the cloning operation from being completed.
A drive that you're really struggling with may therefore not be a very good candidate for cloning. It may be wisest to begin instead by copying your most indispensable data to CDs or DVDs so you'll be certain it's backed up even if cloning later fails. Once that's done, try cloning the whole drive.
Ideally, you would always repair the drive and the permissions on it with Disk Utility or another utility application, run the routine maintenance tasks, and generally make sure the drive is in top condition before cloning it. That minimizes the number of problems that are replicated on the clone.
Directory damage can be caused by an incipient failure of the hard drive itself, and when that's the case, it will probably recur soon after directory repairs are made. If you suspect a drive is on the verge of failure, but you've already backed up all or nearly all the data on it, use Disk Utility or a third-party utility like Diskwarrior or TechTool Pro to repair the drive's directory, then finish backing up or re-clone immediately, to be as sure as possible that your backup or clone is good. If problems reappear very soon, be suspicious of the drive hardware, which no software utility can repair.