Idle speed is way-to-high. It's up against the converter in-gear and tring to move the truck- basicly your "power-brakeing."
Check the list above. Choke, idle setting, vacume leaks, and the throttle bore for wear.
I think the normal out-of-gear idle speed should be around 650 - 700 RPM after the choke lets go.
<font color=blue>Twiz</font color=blue>
Can't get it up?
So, drop it in
gear.