what exactly is the bac valve for? is it really needed? im told it is for helping control idle somehow, but im not getting any straight answers from anyone.

 

to my understanding it helps control idle so that additional stains on the engine (power steering/ air conditioning) dont affect it

 

yep

 

Exactly, it is used to compensate for these additional devices.

 

what if your power steering and a/c isn't connected? im having a hard time getting this motor to idle under 1500rpms. this is a fresh rebuild. is it not going to hold a low idle until it is broken in? what is an ideal idle range for this motor anyway? btw, its an 88 gxl

 

check for vacuum leaks

 

Did you adjust your TPS? you might just try to screw it out a turn to see what happens. Are there any other symptoms? example: Bucking, bogging, dying, smoking.