1992 Cherokee Speedometer problem

I am having a problem figuring this out.My 92 cherokee,4.0,5 speed,the speedometer will stop working and when it does this,it won't idle,like stopping at a red light it dies,cranks back up with no problem .then you may go 1/2 mile and it starts working again,and when you stop, it idles just fine.it has done this for about 6 months.A few days ago the speedometer quit working and has not came back on,and it will not idle.Now when you 1st.crank it up it idles fine.but like I said you come to a stop it dies. I just put a new speed senor on it,didnt help. Anyone got any ideas?I sure would appreciate it.
Thanks
Wayne

check the engine grounds for the pcm (passenger side of block 3 or so wires on a stud nutted together) mine acted simular and I had a loose conection