Ditto carringb and the bear II...
Fan clutch. I have a '95 5.8L with E4OD. Right when I first crank the motor, the fan clutch briefly kicks in, sounds like a Hurricane spooling up in the Gulf!
When towing the hills in the heat, you can hear it kick in again periodically, roaring until the temp drops back down. A quick backyard mechanic test, with the engine stone cold, and
off (thank you very much), grab the fan and rotate it by hand. It should have a fair amount of resistance. If it rotates freely, clutch is gone. Get a new fan clutch.
Even with the 302, your van should be able to handle a 7x16 cargo. Won't win any races, but should handle it reasonably well. Mine does pretty well, towing the same size cargo, and there's an old forum member who used to regularly tow a race car on an open trailer with his 302/5.0 van of same vintage.

If you haven't ventured to the cargo conversions forum, check it out. Several have done handicap accessible units.
tnttt.com cargo conversionsHey, look at that, my post time stamped at 3:02 how cool is that?:C