Does this happen only at 1700 rpm or at all higher rpms?
Try changing your ignition coil if that wasn't changed. It could be on the verge of burning out. It's cheap and probably due to be changed anyway if you haven't done it yet. When they get old, they don't put out enough voltage to produce enough spark at higher rpms.
If it's a fuel pump problem, it's highly unlikely that it's the pumps in the tanks. They are very dependable since they're constantly cooled and lubricated by the gasoline. Of course if you run out of gas often, then they'll poop out much sooner, but to have both go at the same time is quite improbable.
It could be the main engine fuel pump giving out. I think your engine still has the "old fashioned" engine driven mechanical fuel pump. If the diaphram is going bad, then you'd most likely have gasoline leaking into the oil pan which will raise your oil level, so check to see if your oil level is rising.
Try changing the fuel filters. I don't remember where the main fuel filter is on the older trucks. There might also be a filter at the fuel transfer valve that could be clogged. There should also be a filter where the fuel line goes into the carburetor. It's probably a bronze filter and if it's clogged, you can easily remove it and clean it out. This one only comes into play when the main filter media fails.