Please don't bash me as this is my first car, just having some trouble understanding either how to shift or if the TV cable might need adjusting( I did some research on it).
It's an 86 Camaro with a 2.8 tpi v6, I drove it for the first time today after getting it, and I had it in the Overdrive gear {D}, I started out and as I was going down the road I pressed the pedal fully and the car went like max 40mph. Could it be the TV cable or am I supposed to start out in normal drive D and then shift into overdrive {D} at the appropriate speed? No I wasn't manual shifting.
And does drive D take the car through all the gears except 4th gear (overdrive), and the overdrive {D} takes the car through all of the gears plus overdrive?

 

Yes to both your last questions. What was the top RPM when you were maxing out @ 40?

 

It was like 4,000 I believe, I'm not 100% sure though.

 

If you feel no slipping, I would check the 2-3 shift valve, might be stuck. Check the separator plate and the gaskets for cross leaks.
Then the governor valve, just because it's easy to get out and check. Probably not the governor valve though, because you do have a 1-2 upshift.
From there on, it's full rebuild. Might be a damaged piston seal in the 3-4 clutch.