truck falls on face

[TheStig88]

durasparked 2.8
been betting a steady 15 mpg
idles screws 2 3/4 turns out
decided to re-jet from stock 50's to 47's


after rejetting now during slow to gradual acceleration the truck stumbles and falls on its face for a second then accelerates when i put my foot down.
happens in any gear at any speed

never did this before and i changed/adjusted nothing else

before i start troubleshooting i was wondering where i should look first...

 

[TheStig88]

just went and checked....

maybe my problem could be the fact its a 1.21 venturi carb

 

[user111]

I have noticed that if I try to run leaner with lower jet, it effects the carb, When you accelerate slow your using less your accelerator pump, maybe its not pumping the way it should Maybe you can look down inside carb while you move the gas slowly and see if there is a slow steady flow of gas out of nozzle as the accelerator is moved while watching it, I suggest you do it while watching, if someone pushes on gas it could splash in a persons face,

Did you readjust the idle to its highest vacuum reading I have found idle adjustment really does effect gas mileage a lot, and general lower speed operation like city driving.

 

[BichoBII]

Hey man, do you still have this setup? i have a similar setup and im dealing with some knocking on 46 jets at 9100 feet...