Code 37 is one of those codes I've learned to disregard in these years because the circuit isn't used, like a code 34 would be on a vehicle not equipped with speed control.
What you've described very well is what I'd expect on a vehicle that's losing fuel pressure, big blue. As fuel pressure and volume decrease, the fuel system's ability to deliver enough fuel to support higher engine loading is the first to go... you'll find the engine is a bit "soft", losing power and surging. Eventually it won't pull itself in any way, but may still idle. And eventually even that will pass.
Since the same power source feeds the injectors, ignition coil and fuel pump, it doesn't seem likely you have an intermittent loss of power to the pump... at least from the source (the ASD relay). The relatively slow nature of the stall suggests a pump that's very weak and can only support the 15 psi of fuel system pressure it's designed for for a short time before conking out.
If at all possible, buy or rent a fuel pressure gauge that can be placed in-line at the throttle body with your fuel supply hose. The hose size is 5/16" and you'll need a couple feet of extra EFI hose to do the testing, along with the needed clamps. Drive it until it starts acting up and check your pressure. If it's falling, momentarily squeeze the smaller return hose coming off the throttle body in the same area. If it makes no difference, the problem is that the fuel pump is stalling out, not that the regulator is stuck wide open.
If you need to replace the pump... it it seems pretty likely... let me know if you need any help.
I'd sure appreciate it if you'd check the pump again. Be sure to check it when the engine's acting up, which is the time we most need to know about.
The temperature factor is a bit odd, but might be explained by low fuel pressure or fuel quality. Low fuel pressure might not provide enough volume at the injectors to make the engine happy on colder days, but it's a bit of a stretch at this point. Let me know a couple more things about your van if you would...
Describe the hard <bang> you feel when stopping. Does it feel like a manual transmission you forgot to push the clutch in? Does it feel like it wants to push you through the intersection?
See what you can find on the fuel system and we'll talk in a bit.
That hose to the manifold is very important in cold weather and especially in cold, damp weather. I doubt it's your whole problem, but... information only.
Reading your most recent post reminds me of a restricted exhaust system (or a bad fuel pump). You might slide under the van and give the catalytic converter a <thump> with the side of your fist or a soft mallet to see if anything rattles inside. Cats from this time period tended to break up internally, forming smaller chunks that could rattle around and block exhaust flow depending upon the mood.
A restricted exhaust system will cause the EGR valve to flow more exhaust into the intake tract than it should, which will tend to amplify the problem at lighter throttle loads.
The EGR is also a great place to take an exhaust system backpressure reading. The metal valve has a small tube coming off the base that's open to exhaust system backpressure and (not surprisingly) feeds the backpressure transducer, the plastic valve just forward of the metal valve.
If you have a 0-10 psi pressure gauge, connect it to this port and test drive it to see what kind of numbers it gives you. Normal is 5 psi or less at heavy throttle load, so let me know if you see anything above this.
Yes, more homework.