1st gear slips when cold

[abae]

Hello all,
The car- 87 300TDT 603 engine 313,000 miles.
I have only had the car for a year so I dont know the history. I have recently replaced the vacuum hoses, lines, fittings, VCV, and changed the transmission fluid (synthetic) and filter. A short time after I started having problems. When the car is up to operating temp it shifts flawlesly, no flaring or harsh shifts. When driving easy you cant even tell when it shifts unless you are paying close attention. When the engine/transmission is cold I have to drop the gear selector down to 2 to take off and manualy shift up or it just revs and doesnt move. Once warmed up I leave it in D and it works great. Does anyone have any Ideas as to what could cause this?
Thanks in advance.