91 3.0 le baron Shifting Problems

Hello,
I have a 91 Le Baron 3.0 The trans seems to work ok until you come to a stop. When you you push the accerater the trans seems to be in second it roughly slips down into first. Once on the road it fine, what can be done to correct this prolem or smooth out the shifting process.
The trans was rebuilt a few years ago and the car has been sitting dormant up until now. Please advise!
Fastback 27

Hmm... well you could get some of that "kool-aid" and put it in your transmission. That's usually my dad's first solution for small problems like this. They call it kool-aid because it looks like grape kool-aid. It's some kind of transmission fluid additive for smoothing shifting and stuff like that. It's in a little clear bottle, purple liquid. You most likely have the A604 transmission, electronically controlled, so the shifting issue may be a computer / sensor problem. The A604 is known to be one of the smoothest shifting and most problematic transmissions. Ooh and check your trans fluid, is it muddy?

One more thing, I have had a kind of (not really) similar problem when the shifter cable was not adjusted correctly after removing, rebuilding, and replacing my A604 transmission. My car would go into limp mode (2nd gear only) because of it.

EDIT: Dear me, you have the 3 speed? Why didn't you say so? So it's probably not electronic. Put some kool-aid in there and see what it does.