ok so i have a 1982 Mazda rx7. it has a gm kinda jerry rigged alternator i just put a new belt on. but anyways i fixed the alternator problem but the new problem is my rx7 usually idles at about 200 or 300 rpms... and lately it still does but as it warms up a little it starts to idle around 900 to 1000rpms in neautreul. is this normal? if not what is going wrong and what can i look to fix or buy. thanks a ton need help asap! tim. btw maybe im just worrying because i do know they run hot lol but any help still appreciated. thanks!

 

Should idle at 750 rpm or so once warmed up.