Old ford fiesta stalls when i come to a junction engine revs die if i rev up

Hello, yes the problem could me related to a vacuum leak around the intake manifold or carburetor area. What technicians often do is listen for vacuum leaks or spray some carburetor cleaner spray (can) that you can get at an auto parts store around the rubber vacuum hoses to locate the leak. If the engine speeds up when your are spraying, you have located the leak.
The other problem that likely comes up is the EGR valve opening up too soon or when the engine revs and this causes the engine to cut out. You can block off the EGR valve to trouble shoot the problem. If blocking off the EGR valve solves your problem, then you know where the problem is.

You may have a vacuum leak they are common on old car replace all rubber vacuum line they are cheap and you may be surprised what you find.