Dealing with Ghost Viking as Protoss

Hello,

I'm a high masters protoss and I have huge problems dealing with a certain terran composition. My win-rate is at about 80% but that's just because I'm very strong at abusing terrans early game. If I go into late-game and they build the really heavy ghost-viking composition with just a few marines and marauders, I lose immediately.

I don't know to deal with it. Here's what I struggle with:

- Colossi: Get shut down by the vikings within seconds.

- Stalkers: Not viable against terran as "army unit". If I try to use stalkers against the vikings, all my colossi are dead until I killed like 50% of his vikings.

- Archons: Get EMP'd and die immediately.

- Zealots: Get EMP'd and eaten up by Ghosts (Snipe) \ Marines \ Marauders

- HTs: Not that effective, even if I get to land a storm or feedback between the thousands of EMPs, medivacs will heal enough to mitigate the damage, since ghosts have enough hit-points to withstand a storm or two.

The most common answer to this is: "Don't let him get to the massive army, kill him before he gets there." or something along those lines, but I just don't want to believe that there's actually no way to deal with that army. I mean even against a protoss death-ball you can do SOMETHING. But against that ghost / viking composition I just trade my whole army (whatever the composition) against max. 30-40 terran supply.

Would appreciate some advice!

Greetz,

- Nico \ Mercury