2001 Hyundai Accent transmission

While my car was still under warranty, on at least 4 seperate occasions, I had to take it in for diagnostics to determiine the cause of rough idleing and engine revving while sitting still like at a traffic light. Each time I took car in for service they replaced what they called a pulse generator assembly. They said it communicates between engine and transmission. Is there another name for this part and where do I find it on the car? I have recently had to replace the transmission and if this part is on the transmission, I would like to remove it before I junk the old transmission just in case I need one at a later date.