GMC Repair: GMC Pick Stalls, gas filter, pump fuel

Question
Hello Pete, I have a 1986 GMC 2wheel drive half ton pick-up.  It has a V6, and I have changed the coil, wires, plugs, distributor, rotor and cap.  I also replaced the electronic spark control, the fuel pump, fuel filter, and a  mechanic told me that he rebuilt the carb.  The truck has 60 actual miles on it.

My probelm is that my truck may stall at any time.  Sometimes it will stall when I first start it, and later run fine.  At other times it may start out running fine, and stall later while I am doing 60 mph on the interstate.

When it stalls, it seldom cuts off, but runs almost at an idle pace.  It feels like it just quits getting gas when it occurs.  However, I can drop to neutral, and rev the motor.  It has no pull when this happens, and if on an incline, it will drop to a lower gear, and sometimes I cannot pull it.

Sometimes, it will backfire, but not often.  And I have also notice a hissing noise coming from the carb when it stalls.  It sounds as if someone is spitting.

However, when the truck runs good, it runs very strong.  I recently drove it on a 200 mile trip and it ran fine.  However, the next day, it started doing it again.  

I will appreciate any advice.

Thank you.

Answer
hello
when the mech. rebult the carb did he do it the right way i would check the bolts on the plate of the carb to make sure they are not sucking air . and i would check the gas filter which goes in to the carb. let me know please rate my serivice pete