My 85 2.5L 5 speed S-10 has a random problem with loosing power while I am on the highway. I notice that the truck is slowing down and when I accelaerate it does not provide any more power. When I let off on the accelaerator it dies and will not provide enough power to get out of first. If I let the truck site for a while it seems to clear up and works fine for an undeterminded time. I have a new fuel tank so I know I am not picking up any junk in the tank. Any suggestions on what could be the problem?