'87 Vandura, Stalls under load

[damemorder]

We've got an '87 GMC Vandura Conversion Van, It's been sitting for about two years with no prep. Our '83 half ton just lost four bearings and froze so We pulled out the van to use it 'til the truck is back on the road. It took about 5 minutes worth of cranking to get the van to start. Now it idles well enough and will rev in in Nuetral, But under load, like driving up the 12-13% grade to back out of the driveway, It stalls. It feels like it's barely running, and sounds almost as if it has an aggressive camshaft installed.

A little about the van.
Exhaust rusted off after muffler, Cat so clogged it blew the plug out.
Fuel filter just changed, Has good gas in it now.
got new cap, rotor, plugs, and wires just before it was parked.
PVC port in the carb is jam packed with something...


What do you guys think needs done to make this van drive for a few more years?