Engine shuts off when shifting transmission into gear

Pull up a chair. Van went into limp mode and showed engine codes suggesting Solenoid pack was bad. I bought one and installed it, pretty easy and cheap vs a $1,200.00 quote for the work. A roommate gave it a test drive while I was cleaning up and came back and s. Aid it drove just fine. When we went to start it, the van was completely dead which was eventually tracked to a the negative battery terminal somehow losing contact with the grounding bolts, a little time with a file to take some paint off and problem solved. However, during the time trying to track it down I dove into the electronic connectors under the dash where the BCM lives and disconnected and reconnected some of the large connectors there. Once the grounding issue was fixed the van started right up but we didn't drive it for a few days thinking all was well since it had performed fine on the test drive. My mom drove it and said started out rough, surging and jerking but smoothed out and she drove it about 15 miles and other than starting out a little rough it seemed okay. I finally got to drive it and it was a bit the same way to start, a little surgery and jerky but seemed to settle down but then started dying when placed in gear with the brake on, D and Reverse. Kind of a clunk and shudder and the engine stalls. Sometimes coming to a stop it would idle normally in neutral but buck pretty violently when pulling away from the stop. Sometimes I would have to start it in neutral, rev it up and drop it into drive without the brake on and just hold on is it jerked. Once up to speed it seems okay but starting and stopping were a challenge and right now I'm nervous to actually drive it anywhere. If I start it in the driveway and put it gear, it stalls as described above. I have taken the air intake off, re-seated the solenoid pack connector and speed sensor connector, and taken the dash under the steering wheel off and tried re-seating connectors there as well with no luck. I'm not sure if there is a bad sensor or the solenoid pack relearning is a really rough process - but it did the initial drive after the install without this issue. I may have messed something up pulling connectors under the dash and it did sit for a day or so with no power while I figured out it wasn't grounded. I'm not quite sure what to look at next and am open so suggestions and ideas.