Ok.. so, I've got an 86 351w, took off the stock carb, and put on a Holley 670 CFM Truck Avenger carb.. and it bucks real bad, esp. when a little cold, or for example, if I'm in 1st gear, just idling and rolling forward and try to stop it, it'll lurch forward, then pause till I let off the gas, then lurch forward a foot or so then idle forward again.. also, if moving slightly slow for 3rd/4th gear, and try to punch it, it bucks a lot until the RPMs are higher..
I've got the vaccuum ports hooked up right, except for the PCV Valve, I've got that unhooked, as I'm broke, and so is it. Although the port on the carb is plugged.
Any ideas on what the problem could be? Doesn't seem to be any mis fires, idles well, not rough or anything, timing should be good, it was set just recently.. any help would be greatly appreciated, 'cause I really need the low end power on this vehicle.

 

If the rest of the engine is stock, you have a strong possibility that you over carbureted the engine. You might be dumping a puddle of fuel into the intake manifold. The Holley T/A 670 cfm carburetor is for engines between 300 to 400 horse power. I think you should get a 500 cfm 4bbl carburetor with vacuum secondaries. Or give Holley a call and talk to a technician.

 

hook up your pcv
do you have a egr if so does it work
check your accellerator pump lengthen the stroke
is your timing adv. enough, idle problem sounds more like a timing or incorrectly adj. air screws

 

Ok, I redid the timing, and some carb tuning, got that problem fixed..
But I noticed that after I push the petal down as far as it can go, then go out and look at the carb, it's still got another inch or so that it could go.. and.. I can always use more..
Anyone know a good way to fix that?
It's an 81 F100.