I feel your pain, after Tuedays jaunt i noticed a frayed cable on my front mech so decided to replace it, got in a right mess and had twiddled the little screws more than i can remember in ever direction and generally lost my rag with it. Last night i spent about 3 hrs on it much to the annoyance of Mrs but i think i have solved it, its not quite 100% but damn close, this is what i did (finally)
1) undo cable clamp from frotn mech and release cable
2) wind in then back off 4 turns ( 2 may be adequate but 4 gives more !) the adjuster in the shift leaver.
3)put the shifter to the center gear and put the chain on the center cog and position the mech BY HAND so its central and then clamp the cable up firm.
4) back off both limit screws by about 7 complete turns, right out ! (they are limit screws not adjusters, they only limit the movement of the mech they dont adjust anything !)
5) check the derailleur is aligned properly front to back and side to side, adjust frame clamp if necessary
6) shift onto the small cog up front (large in rear) and adjust the 'L' limit screw inward so there is 0-1mm gap between chain and cage, this setting stops the chain falling past the small cog. Test your limit by turning the crank and shift up BY PRESSING ON THE CABLE (never use the shifter at this point) the chain will shift to the center cog and as soon as you release the cable it will shift back down again, should be a smooth action taking no more than one complete turn of the crank, you can speed it up by adjusting the 'L' screw if it takes too long (i settled on 1/2 a crank revolution ?)
7) now shift up to the large front cog and small rear cog and adjust the 'h' screw the same as you did for the 'L' screw so there is a 0-1mm gap between cage and chain, check adjustment again by shifting back down to the center and then shifting up by putting pressure on the cable (not using the shifter) , you can adjust the 'H' scew to allow the derailleur to move further outward when under tension if the chain doesnt shift up smoothly, until it does
Hope this helps, it got mine working again but i get a very small amount of rub in top gear that i may be able to adjust with the cable tension, was getting moaned a t so never got that far.
P.S found this online which basically (better? ) describes the adjustment in english....
http://www.parktool.com/blog/repair-help/front-derailleur-adjustments