Cruise control continues to accelerate when activated.
Get that car to a mechanic ASAP
Since the 79’ Bird was only capable of what are “normal” highway speeds these days. You should be fine… let her rip
Does the cruise control just have the one button on the end of the turn signal switch? If so, the button is likely sticking.
Ok, thanks I will look at it. But it is a new signal and button
Factory cruise control? If so, this may be caused by the transducer mounted on the top of the left front fender under the hood. Two cables; you can’t miss it. They are known for being a bit flaky and a simple way of keeping the real miles from showing up on the odometer as many people disconnected the TD so as to have a “low miles” car.
There are some check and service procedures but since this is ancient history I remember none of it.
Thanks for the reply. I also thought Transducer. I can’t find one to purchase and called Cardone and they won’t rebuild it because I don’t have an account with them.
I had the same problem with my 1982 Toyota Cressida (I still have the car). I had to buy a new cruise control computer. Shortly after, NHTSA received complaints and Toyota denied there was a problem. When I found out about this, I wrote to Toyota and never heard back.
So even though there are three Toyotas in my family, I am NOT one of those who claim that Toyotas are superior to the USA brands. Being a fan of RWD cars, my next new car may be a Ford Mustang.
The only problem I had with my Chevy Chevelle was with the Rochester carburetors (I went through three of them in 140,000 miles. Aside from that it was a great car.
Thanks Tom
There’s a guy on eBay who rebuilds those things I believe. A 120 bucks or something like that. Seems a bit pricey for what’s involved with a transducer, but…
You might make sure both cables are properly lubed with graphite and rotate smoothly. I think (?) there is a small air filter inside the transducer so maybe checking that to see if it’s clogged up after 40 years might help. Make sure the cable drives rotate smoothly in the transducer and lube with graphite if necessary.
My memory is very sketchy on this as I have not touched one of those things since the last dinosaurs died out… 
Ok thanks I will give it a look and a lube. Like to get it rebuilt. Will try and find that guy on ebay.