'85 K30 454 bogs under load

[gloriavoxdei]

Hi, I have an '85 K30 crew cab dually and when I'm climbing a hill or the truck is under load it feels like it's going to die. If I back off the throttle it's fine but as soon as I get back on it the same thing happens. I just replaced the fuel pump Saturday when I bought it and didn't notice it then. My ignition timing is at 12 adv when the vacume is hooked up to manifold vacume and 8 adv when unhooked. Help me out here, I'm getting anoyed.