That is the TV (Throttle Valve) rod. When you stomp on the gas, that rod initiates what is known as "passing gear". It downshifts the trans at higher RPM's for torque purposes. When you let off the accelerator, it allows the trans to go back to normal gearing.

 

I finally read a little sticker that is by the rad that looks to be instructions for adjusting the carb idle. It is very faded and half of it is missing but it refers to vacuum controlled something. So I am assuming the idle rpms are vacuum controlled which is above my abilities haha.

 

I could not tell from you pic, is your carb a 2 bbl or 4bbl? And just for my info which engine do you have? If it is a 5.8lL HO (351w) with the 4bbl carb I can get you a photo of the emissions sticker (the faded one you found)

 

It is a 302 so I believe that is a 2bbl. Thanks for the offer though! That would have been very helpful.

 

If you queery on line your year make and model about DIY adjust engine iddle you will get a host of u tube DIY's on the subject or a model year that uses the same as yours.

 

My issue wasn't exactly what I thought it was haha. Turns out the alternator was affecting my idle. I never realized that my alternator wasn't charging until my battery finally died, which takes a while in these trucks when you don't drive them at night and its a brand new battery. Not a lot of power is drawn. But I found a wire that was pulled out of my voltage regulator wire harness, which stopped the charge. As soon as I plug that wire back into the harness the engine idle comes back down to normal due to the load I guess. The truck has been put away for the winter now but I will play around with it more in the spring and try to get that wire to stay in there.