When I am going down the highway, my truck looses gas flow, this is of and on. Only on the highway whenI am at a constant speed. It idols smooth. I recently put in a new long block, new plugs, wire, oil, trans fluid, antifreeze, egr valve.
I had all the vacuums replaced and professionally done.
Any ideads?
91 s-10, v6, 4.3l
Thanks