Is it the head gasket ?

Hello everybody. It's obvious that I'm no mechanic; I bought a 1989 Turbo Supra and love it so far. Lately it stops running if I turn the steering wheel while idling, and sometimes if I make a sharp turn without giving it extra gas. I was told this was due to a low idling setting. This particular model is supposed to maintain its' own idle setting somehow because it cannot be adjusted by screwdriver. Do you think that this is a computer problem, or could this problem also be remedied by a metal head gasket ? Thank you very much for any help.

when you are at a stop and at a idel, what is the rpm's at? If it is not ideling where it should, it could be the tps sencer. That controls where the throttle shold be.

Check for vac and intake leaks.