I'm leaning towards crank sensor too. They are sensitive to temperature when they start to go bad; no signal from the crank sensor and the ECM will shut everything down (spark and often fuel too). Since you use it for a mail route, the temps under the hood will be warmer than if you were driving at a steady 50 mph, so temperature-related failures will be much more likely and you will be more sensitive to them.
However, since you have just recently changed the fuel pump, there is a chance you got a bad pump out of the box; also, since your gas gauge is not reading right, I would double check the electrical harness at the top of the tank (where the fuel pump and sending unit plug into the harness) and also check the ground strap from tank-to-chassis. Also, and this is occasionally overlooked, but when the car loses power, what'* the fuel level? Are you over 1/4 tank? Fuel in the tank keeps the fuel pump cool; if you have lower fuel levels, the pump runs hotter, and will fail sooner. (Speaking from experience here, I've been a substitute driver for a few different newspaper routes.)
Another thing you may want to check is restricted exhaust. Because of the increased temperature of a car that doesn't have much air circulation around it (low speeds and lots of stop-and-go), plus the car'* age, you may have a bad catalytic converter.
Yet another possibility is a failing Mass Airflow Sensor, which sometimes doesn't set a trouble code. All I can offer is possible solutions without a little more info. Is the Service Engine Soon light on? The Security light? When you say it gets progressively worse, is it a sudden loss of power that then gradually gets worse and worse? Or is it pretty much a steady decline in performance from a cold start?
Don't go throwing money at the Bonnie though, until you do a little further diagnosis. I'd hate to see anyone replacing a myriad of parts in the attempt to fix a problem, and not many people have disposable income like that!
Also, the sending unit float may be rubbing against the internal "basket" it sits in. *IF* you drop the tank again, pull the sending unit out and move the float slowly back and forth in its full range of motion for several minutes. I've had great success in fixing "sticky" fuel gauges this way. But this won't cure your loss of power...