I bought a rebuilt a 413 for my 1990 Plymouth Voyager turbo and installed it last weekend just got everything put back together still having some vacuum issues but all in all runs good just not shifting right.

seems to take off in second gear and at a very slow roll if you pull the gear lever down into first it feels like you are pushing the brakes as it will slow the vehicle to a stop. Doing the same thing from D into second at a very slow roll same scenario but not as much slowing.

I did install a shift technology products shift kit before I installed the transmission. I went by the instructions and took my time. Fairly straightforward and simple installation.
I am really hoping that someone else has experienced this and can give me some tips. The transmission unfortunately does not have a warranty but the work was done by a respectable transmission shop locally. I am completely out of time to work on this van, I don want to give up on it but I am completely out of time and money.

this project was supposed to be quick get it looking good and running good and be a reliable fun DD, so far it's not working out so well.

I really need to solve this! Help!
as always thanks in advance for any and all information!