Mitternacht

On my 98 Gt, after I get out of whatever gear I was in, and come to a stop, the engine goes from 1000 RPM to 600, and back up. It does it 3 times and then its fine; it will idle at 900 afterwards. There's a lot of mods in it, and there are newer cams in it. I'll have to post all of the performance parts later. Any ideas on what makes idle out of whack?

Willis_98GT

mine does that too. i'm clueless also