All the advice on setting up the derailleur to shift properly first is golden. Limit screws, proper height angle, good cable routing and lubrication of pivots and springs have to be resolved first. In regards to FD height, the outer cage should clear the longest teeth on the big chainring by just a few mm. IE, when the chain is on the big ring, you should not be able to move the FD inward to flex the chain without turning the cranks. The closer the FD to the chainring, the better the shift, especially with large steps between chainrings.

Some shimano front derailleurs actually swing outward slightly as they actuate. This is not a design flaw, it allows for more useful gear combinations while still keeping the limit stops close. Its also important because you can't precisely trim with STI. (The rear of the cage is farther out from the centerline of the frame).

Its a very slight arc, but generally the FD will only be perfectly parallel with the chain rings in its low normal state. In regards to setup, make sure the FD is parallel with the chainrings in its low normal state. FD's that move in this slight arc (in plan view), may not shift back to the small chainring unless they are set up in this way. My FD7700, and I think my FD7800 have this characteristic.

With FD's that stay perfectly parallel, maybe try setting it at a slight angle (with the rear of the cage being 1-2mm further than the front from the centerline of the bike). This can resolve upshift problems, but you will need to let out the inner limit stop to prevent rubbing in your low/low combination.

It can also be a problem with the shifter. I have had older 9speed 105, and 8 speed 600, have backlash issues. Any ratchet mechanism has backlash, or play between the ratchet and the pawls. This manifests itself in derailleur movement in a way thats like 3 steps forward, 1 step back. Most of the time, its actually good for shifting because you need that little bit of extra push to get the chain to catch onto the big ring. However, backlash increases proportionately to wear, so your older shifters may shift up to the big ring, only to fall back down as you release the lever; further tensioning of the cable only makes the FD overshift.

There's not much you can do to overcome backlash issues except replace the ratchet and pawls, and you can't do that with shimano except for some 8 speed models and 7700 9 speed. Don't buy used low-end STI levers; most of the time you'll get them when they're ready to fail.