i have a 1984 dodge ram. i put on new sending unit fuel pump fuel filter rebuilt carb. the problem i have is... going down the road , when the truck shifts into high gear it shuts down. at about 40 mph. it idles real good and only does it underload..... please help thank you

 

have u checked the timing? did u put a new sock on the fuel pump? vacuum leaks? intake manifold gaskets? just a few ideas to check