there could be a million things, but being and 85 i8d take a look at the power stearing pump it could be going out and during a turn it could start to lock up and thus transfer this to the engine via the harmonic balancer.

You could also have an exhust leak only during a turn it is actually possible, during a turn the engine has to also move and then it returns straight, how are your motor mounts?

Look for the noticeable items first before you go digging in, though i really doubt the exhust has anything to do with this. you also could have a bad wire harness and during a turn the engine moves just enough to short out.

It could also be a bad intank fuel pump, there not supposed to stall the car but if its bad and your main pump isnt pumping full pressure you could stall then.