First off let me start with what i'm working on. I have a 86 blazer with a 4 barrel quadrajet off a stock 305, the one with the dual capacity pump. I have run the Dual capacity pump to a switch on the inside of the vehicle so I can operate it manually. I have installed a Gm crate 350 HO, the one with 330 hp.350 HO Engine specs I'm having problems with to lean of a mixture from a standing start and part throttle tip-ins in 4 gear. THe thing stumbles an then goes, sometime it dies out when its not warm or when I try to floor it. I've noticed that I don't have these problems as bad when the choke is on, thus a richer mixture. When I leave the dual cpacity pump off, richer mixture, i don't have the problem either, but this makes the mixture too rich at idle and it waste alot of gas. I tried adjusting the APT (adjustable part throttle), and this seems to help some until the tempature drops and then it starts the stumbles again. i have a pretty good idea that the jetting and primary configuration are too lean. I have .072 jets and .051 primary rods, i checked that out today. I have read that the difference in these two numbers needs to be close to .03 and I have only .021. I think this is causing the lean mixture off idle. I know that the transition from idle to part throttle requires the richest mixture, or at least thats what Doug Roe's book says. Anyways, the real question is, can anyone suggest a jetting and rod configuration that might help me out here, or do I have other problems. Also I have a feeling that the secondaries are lean also. I have the DP rods which have a minimum diameter of .0686. Is this going to be lean at full throttle, any suggestions. Thanks for the help in advance, and sorry for the long post, but i know you guys hate it when people don't give all the information. Here are the engine and cam specs again specs .