96 protege idle
 

My 1996 Mazda Protege has a very bad idle. When I crank it up, the idle is very high then after about 15 minutes, my rpms go down to 1000. From there, they start surging up and down up and down up and down. It does this while in gear's P-R,D-1. It doesn't do this in neutral. Whenever I put in in neutral, it smooths out but my car still sounds very loud. When I make deep turns or stop at a stoplight or stop sign, it acts as if it wants to cut off. (Most of the time it does) And there goes the rpms again. Also when I turn on the a/c, my rpms go down and I have to put it in neutral so it will not cut off when I'm at stop signs. But if I do it while its in park, the gears go up and down and I have to keep my foot on the gas just to make them stay steady at 1000 rpms and not go down. You basically have to drive this car like its a stick shift by shifting into neutral AFTER coming to stop signs or stop lights and preparing to shift into neutral when you are making DEEP turns. What could this mean??? Please help me. I'm 13 years old trying to fix this car so that it is fixed for me when I turn 15 in one year.