1983 Toyota Pickup Sputtering & Stumped.

I've fixed many a problem with my old '83, but this one's really giving me a headache. The motor starts fine, first thing in the morning, even on cold mornings, and the truck will run ok until I turn it off, sometimes even the first time I come to a complete stop. After this point, the engine sputters and resists acceleration, causing the engine to slow, and sometimes stall. However, If I gun it up to the red line through 1st and 2nd gears, the sputtering and resistance problem ceases, and the truck will run fine, with a slight reduction in power.
I've already tried:
New spark plugs & wires, new fuel oil and air filters, cleaned and tested pcv valve, regularly greased bearings, regularly changed motor oil, and gear oil in axles, tranny, and transfer case.
So the simple stuff is pretty much eliminated, now I'm thinking carb troubles; if anyone has any additional ideas or insight, it would be greatly appreciated.