1990 Miata

Have been to 2 shops without results- when I turn on the AC - the car loses all power (not just a little) - won’t go above 10 miles an hour - then the fuse will blow - did replace fuse - then tried again - just fine for 5 minutes - cold ac, etc. - then lost power and blew fuse- if you turn off ac and turn off and on 5 to 10 times - will go back to normal running so long as you don’t turn on the ac. Now after taking to last shop - the idle is surging - at a stop- the idle will rev and decline over and over again - can lift on foot pedal to stop, but will also do surging whenever the pressure to the foot pedal is released during driving - Please Help - any advice will be greatly appreciated.