LAWRIMORE66MUSTANG

I have a 1966 Mustang V8, Edelbrock 4v Carb, Edelbrock Intake. Nothing really performance enhancing, Automatic C4. The issue I am having is that it will shift normally for a while but then all of a sudden the car will shift from 3 to 2nd without me touching the accelerator. This happens at around 40mph. I can completely release the pedal and it will then shift back to 3rd again only to downshift a few seconds later. I recently purchased the vehicle and do not know what has been done to it. I can see the kickdown cable and it does not seem to be overly tight or loose.

What else can I check to see what may be the issue.

Gun Jam

you could check into the modulator. Read up on how it functions. It's likley a possible issue.

Starfury

+1

Sounds like it could easily be a modulator problem.

Keep in mind that there are several modulators available, each identified by colored ring(s) around the outside of the housing.

LAWRIMORE66MUSTANG

Are they pretty easy to replace?

LAWRIMORE66MUSTANG

I looked it up and will replace that first. Seems like the easiest thing to do. Hopefully that is all it is. I will also check the vacuum lines for any types of leaks.