Working so far.
1. Deleted everything exept
wallet.dat (make sure you backed it up and/or knowing your Private Key)
2. Amber.conf:
upnp=0
listen=0
connect=ambercoin01.mooo.com
connect=ambercoin02.mooo.com
connect=ambercoin03.mooo.com
3. started ambercoin qt-wallet with:
ambercoin-qt-win-v3.0.0.3\AmberCoin-qt.exe -connect=ambercoin02.mooo.com
It´s running stable and it´s staking through the official nodes:

getpeerinfo
15:03:03

[
{
"addr" : "ambercoin02.mooo.com",
"services" : "00000001",
"lastsend" : 1448978573,
"lastrecv" : 1448978573,
"conntime" : 1448944016,
"version" : 90001,
"subver" : "/AmberCoin:3.0.0.3/",
"inbound" : false,
"startingheight" : 602508,
"banscore" : 0
},
{
"addr" : "ambercoin01.mooo.com",
"services" : "00000001",
"lastsend" : 1448978573,
"lastrecv" : 1448978573,
"conntime" : 1448944016,
"version" : 90001,
"subver" : "/AmberCoin:3.0.0.3/",
"inbound" : false,
"startingheight" : 602508,
"banscore" : 0
},
{
"addr" : "ambercoin03.mooo.com",
"services" : "00000001",
"lastsend" : 1448978573,
"lastrecv" : 1448978573,
"conntime" : 1448944016,
"version" : 90001,
"subver" : "/AmberCoin:3.0.0.3/",
"inbound" : false,
"startingheight" : 602508,
"banscore" : 0
}
]
That work for me without problem last 2 days. Thank you!