just got a 90 rx7 gxl as a trade and it runs perfect except it doesnt idle smooth at all and if im sitting at a stoplight facing uphill it cuts off if i dont give it gas. Previous owner said there was an exhaust leak and possibly a bad o2 sensor. . would these cause this problem?

 

Vacuum leaks/issue with the AFM/TPS/dirty BAC/etc. It won't be O2 or exhaust leaks.