Trans wont shift when cold

[400/6/PAC]

I have a 400 motor and 727 transmission with manual shift kit.
When I try to shift from 1st to 2ND the car really bogs down and I have to go back to 1st.
I tried going from 1st to 3rd and it works fine.The funny thing is, From 3rd I can down shift to 2ND and it works fine, After that 2ND works normal.
Its like it only does this when its cold. Once it warms up everything works normal.
Any ideas what might be going on?
Could it just be the shift cable.
Thanks for any advise.

[turbobitt]

It sounds like the low/reverse servo is sticking for some reason. In manual low, the low reverse band applies and must release before applying the 2nd gear/Kickdown band. You may want to check and see if there are any signs of the servo cocking in the bore and also if it has a HD spring installed. Another thing to check is the feed hole for the low reverse servo in the VB seperator plate that mates to the case. Should be something like 3/16.  If it is a newer VB in an older case, there may be some passage miss-match due to added check ball feature in the new VB.

[400/6/PAC]

Yes
It does feel like its trying to go into reverse.
Even made the tires squill Yesterday when I was trying to test it.
Scared to drive it anymore untill I get it fixed.