ok guys i have an 86' truck with a 79' motor with aprox 70,000 miles on it well i got it all swapped in the truck runs good at higher idle but wont idle at about 1,000 rpm has to be at least 2... another thing is when i drive it and i hit the brakes the engine tries to die out, but only when driving i can do this wile its idleing and nothing no idle change or anything..it has an electric fuel pump i dunno if this would be any prob, im gonna do a seafoam treatment tonight and see what happens thanks!

 

sounds like a vacuume issue .

 

vacc or carb settings. my bet is on the carb

 

but it would still do it when i stomp the brakes when idling right? or at least change the engine rpms?

 

yeah i just rebuilt my carb a little wile ago but its a mother@#$%#$ to tune

 

agreeing with the vacuum issue and/or cab issue
vacuum line from the booster to the carb attached? working?

 

ok im preeeety sure my carb is running lean wich way do i turn the screw to richen the mixture? and ill check the booster vac line tmr...to late to check now