Ford Repair: why the car dies when put in gear, mercury grand marquis, rubber diaphragms

Question
I have a 1978 Mercury Grand Marquis LS that when you startit it idles but when a load is put on the motor it dies or even when it is put into gear what could cause that the motor is a 302 with about 200,000 miles on it i was thinking it was a vacum leak somewhere it has those lines everywhere. I would be greatfull for you help. Thank you Elijah

Answer
I think your engine has what is called a variable-venturi carburetor. Ford used this carb for only a short time. It has a couple of rubber diaphragms that rupture, one for the choke that most likely is not the problem you describe. The other controls the main jets in the carburetor and works with vacuum. If this diaphragm is bad, the engine cannot accelerate.

This is one possibilty, unless the carburetor has been changed or is a different style. Very touchy carb to work on, if you can even find someone that has the tool kit for it. A vacuum leak might also cause this if you can find one.