[lukecp]

You may want to run bigger secondary jets. Changing the jets isn't very much harden than changine the metering rods, just pull the top off of the carb. I changed the secondary jets in my 1406 from .095" to .098" jets, and it took me less than 20 minutes, and gave the truck more of a "kick" when the secondaries open.

If you say the truck runs great under part throttle, but is lean when the secondaries are open, try maybe some .101" jets in the secondaries. I tried them in my 1406, and they were too rich for my combo and actually slowed the truck down. They may work for yours. Have someone look behind your truck when you mash open the secondaries....if alot of black smoke comes out the exhaust, you are proably already running too rich. A little black smoke is normal on a carbed vehicle, but not too much.