I'd like to get your thoughts on how to deal with this.

I sat down at a 6max game, folded some hands and noticed that the player two to my right couldn't fold, and didn't bet post. Soon after I sat down, another player sits in on my immediate right who also couldn't fold, and never raised. Only difference was she would bet on occasion post flop.
To my left is a tight player, then a TAG/good player, and another tight player rounds out the table.

Just about any time I want, I isolate the two callers and I'm up 15BB.

Then, the tight player to my left leaves and a ************ sits in his place (I'm still p*ssed). He's a raise monkey, popping my blind about every revolution, re-raising so I can't isolate anymore. Every time I'm in the pot, I have to beat three other hands, one of which is going to raise me often, and two others that are going to cold call.
Needless to say, AA, KK, QQ never materialized, my 77 every 10 hands always flop 2 overs no 7...
I lose my +15BB, then bleed out 15BB more. About half way through, the calling station on my right leaves, replaced by an avg. player.

I was able to at least wreak vengeance on raise monkey's last ~$8 as he inevitably busted out. (The TAG player and I tag teamed the monkey as the table broke up).

So, question:
What do I do about a situation like that? I hate to just give up and leave while the gold mines are still there, but I can't beat 3 people with a non-premium hand very often.

don't let the "gold mines" keep you at a bad table.

you were able to win a lot of money from them prior to the arrival of the LAG by isolating them. but once the LAG comes, you can no longer do this, so the players become less profitable to you. it can be tricky playing against a LAG, especially when you are OOP nearly every hand.

your options are to adjust and try and play against the LAG, who will give you a lot of high-variance action, or to leave and find a new table with good position on bad players.

tighten up, adjust your game, and punish this SOB for raising with shit.