Rebuilt '67 C4 will not shift
 

I was hoping I could get some helpful advice with the possible cause of my transmission problems. I have rebuilt my C4 transmission in my '67 Mustang & am having trouble with it shifting. It was a complete rebuild with a shift kit.

When I first drive the car, the transmission will properly shift up thru all the gears. But, when I come to a stop, it will not downshift back to first gear(It stays in 3rd gear). I need to manually shift to 1 to get it back into first & manually shift to 2 & again into D. So basically my C4 is acting like a manual transmission after the first time automatically thru the gears. If I shut off the car & let it sit, this will happen again. Also, it will not downshift from 3rd to 2nd or 2nd to 1st when slowing.

I have pulled out the valve body & verified all the valves & springs are installed properly. I did remove the Accumulator spring when installing a shift kit. The kit called for it to be removed.

I suspect my Governor, but really don't want to remove the transmission again to pull of the housing to check the Governor. I want to be sure I have check everything else that could possibly cause this issue without the pulling the C4.

Any helpful advice for possible testing or adjustments would be really appreciated.

Welcome to the site

Not a modulator issue?