Miata Turbo Forum - Boost cars, acquire cats. - HELP PLEASE idle problem 97 na

I started my car after a drive today and it was idling at 2000. Then when I press the brake it drops to 1500 and then jumps back up to 2000 and repeats until I let off the brake. I tried wiggling the throttle cable around it it would drop and rise like when I pressed the brakes. The cable was stuck under the vacuum hose for the brake booster so I moved it to free the throttle cable. Now when I move the throttle cable it doesn't dip but I'm still at 2000 and it still dip when I press the brakes what can this be I'm at a complete loss. Please help me out on this one guys. I don't want to damage the engine in any way.