alright, it was referred to me to start a new thread with this title to hopefully achieve more people looking and get more advice. heres a copy of the orginal post with my complaints: vehicle: 1985 gmc 1500 4x2 4.3 4bbl 4spd manual factory carb engine. i bought and installed an edlebrock 500 performer series carb (1403 i believe) on my 85 about 4 months ago. never had it tuned quite right. finally iv fixed all my vacuum leaks, removed smog and such. my problem might be because of climate temps or not idk? carb has the rods and jets installed from edlebrock that came in the box. as i come up over a hill and put my food down to try and maintain as much speed as possible it luggs down like i would expect it it. as i crest the hill and gently let off the gas the truck shutters horribly. i completly let of the gas and get back on it and the shuttering is gone. i have no idea why its doing this. im not a carb guy id rather have FI. also noted, if i installed richer rods the problem is worse, rather it has richer rods or original rods: if i change the springs in it (to raise and lower the rods with vac pressure, sorry forgot the name of those) to allow a richer mixture sooner the problem is worse as well. factory rods and the light springs i could put in (leaner longer) usually stops the problem, however one cold morning i had the shuttering problem when ever i let of the gas. wtfs going on? where should i start? did i mention im not a carb guy?