I have 92 305 TBI camaro that has started surging at idle and dies It doesnt do it all the time.Injectors are spraying a nice cone pattern.I have a new IAC and reset it to make sure idle was set correct.Checked the coil and wires and cap and button. Fuel pressure is 12lbs Car doesn't miss and have checked vaccum and I am making between 19 and 20hg when its not surging. When the idle surges the rpms go up to about 1k and drop down to 500 rpms and back up to 750 and then cuts off. You can start it back up fine sometimes it doesnt do it anymore and sometimes it does.I have looked for pinched wires or shorted wires and can't find any.Could the distribator mod or pick up coil be going bad causing this? The distribator is really rusty inside.

 

I have been told that a surging at idle is most likely in the EGR valve but I am not forsure on that.