Have you been fooling with the little screws on the front derailleur? Sounds like the front problem is due to the high limit screw being adjusted out too far.
The rear "hunting" is normally cable-tension; too loose or too tight will cause such problems, as will too much gorpy lube built up.
Try this: Clean up the chain, cogs, etc., and re-lube with a small amount of quality lube. Run the rear DR down to the smallest cog, and see how much play is in the rear DR cable. There should be little or none.