ORIGINAL: DaveG55
While the throttle/brake linkage may indeed be set up wrong that is not why the vehicle dies when applying the brake.
Your problem is most likely your idle, more speciffiaclly your idle gap.
When applying the brakes you fully close the carb. If you do not hav a 1mm - 2mm idle gap the engine will be starved for air and stall. The idle screw is usually located near the base of the carb.
Having said that, there are other things that can cause an engine to stall when applying the brakes. Things like broken clutch springs or damaged/sticking clutch shoes will do it too.
WHAT HE SAID
also check your low speed needle. if you can go back to factory settings and retune, get the car at operating temp. then set ur high speed needle first ,once high speed is set and NOT TO LEAN then adjust idle if neccesary, then low speed needle do this by pinching the fuel line , it should run for 2-3 seconds rev high then cut out , if not then richen a lil bit like an 1/8th turn run it high speed again and try the pinch test again.make sure u run the car each time, to clear any extra fuel that may load up and give you false settings
make sure the car is at operating temp throughout this procedure.
of course keep in mind it could be more than jus setting the enginie to run rite it could be jus a daveg55 said . check out your vehicle and start from there. if you dont know how to tell or what ur lookin at take it to a LHS (local hobby shop)
good luck
Q