[LEVE]

Stalling at highway speed and recovery after sitting could also be connected to the Catalytic Converter. As you're tooling down the road, if the converter is plugged, the exhaust back-pressure can build up. Since the engine is an air pump, and can't exhaust through the plugging converter the engine stops. When you sit at the side of the road, the pressure bleeds off through the converter. Now you can go on your way till it happens again. A couple of ways to diagnose the problem is:

• Have the exhaust back-pressure checked at a mom and pop muffler shop. The test is usually free.
• Lift the hood at night and see if the exhaust manifolds are glowing dull to bright red. That's the heat being trapped. It's harder to see during the day.
• Do the same for the Catalytic Converter, if it's plugged it's going to get really - really - hot and may even start glowing.

One rule of thumb I've followed is:

• If the engine dies like you turned off the ignition, the problem is electrical.
• If the engine sputters and dies like it's struggling to continue, it's fuel related.

so, how is it dying, like you turned off the ignition or sputtering and coughing as you try to keep it going?

This problem may have to get worse before you can find the problem.

 

[LEVE]

Or would the basic fuel pressure check, if within tolerance, rule this out?

I doubt that a fuel pressure check would help a whole lot. You've already replaced the fuel pump, so pressure should be good. Most tests are taken at idle, and not while you're running down the street with the engine under load... hence the problem won't show up.