I dont know if this is the same interview but there is an interview with Harold Ramis on Aint It Cool were he was talking about Ghostbuster 3:
"QUINT: I know you're probably sick of it, but the AICN readers would kill me if I didn't bring up GHOSTBUSTERS 3. I know a few years ago it was getting hot and then just seemed to disappear. What's going on with it?
HAROLD RAMIS: Yeah, Danny and I actually played around for a while... Aykroyd had a great concept. He called me and said, "I got it. I got GHOSTBUSTERS 3." I said, "What is it?" He said, "Ghostbusters go to Hell! This is it!" (laughs)
QUINT: So is there a chance that it'll still happen?
HAROLD RAMIS: Well, the script was viable. Dan is the most imaginative person. He went off on a tangent 90% of the movie is a special effect set entirely in Hell, you know. I had a whole different take on it.
Really, it was the business that stopped it. I never thought that the public wanted to see the three of us kind of stuffed into our jumpsuits again. I thought we would introduce three new Ghostbusters, but maybe we'd be around as Senior Ghostbusters, running the company or something, but the real adventure would be... And this was so long ago, we were thinking Chris Rock, Chris Farley and Ben Stiller taking over. That would have worked
And we had the script all worked out. Danny and I had the story and Murray got really... Murray's so cantankerous, you know. Dan called him and said, "Would you be in the movie?" And he said, "I'll be in the movie... but only as a ghost."
QUINT: That would have been awesome!
HAROLD RAMIS: (laughs) It would have been interesting. So, we even created a story around that. In the end, it sounRAB greedy, but the deal couldn't be made. We as an entity... Me... well, I'm low man on that totem pole deal-wise, but Ivan, Bill, Danny and me couldn't make a deal with the studio. There wasn't enough left for the studio.
And I can't say my heart was really in it, you know... making the third one."