It's a long time since I've played vanilla RFC rather than DoC, but I have a vague memory that you lose stability for each civ you make contact with before a certain point (Astronomy???). You might need to drop contact with some civs.
That is seems odd as a mechanic because I thought I read having more contacts made for higher stability, as did more OB, defensive pacts, etc. Ok well I just found this which says higher contacts incurs a penalty, in part to help "East Asian civs, who having less contacts, tend to develop less trade and get a lower Economy rating." So maybe this means you should not build embassies so the contacts are lower...but in mid/late game that's not realistic, and in game you have to grow the economy via trade.
@ales_ I think oh my godWhat is OMG?