That's a good question. I had my 98 Tip Tran rebuilt a couple years back... so this is my advice...
Don't disconnect the battery. You MAY/MIGHT/WANT to have the transmission codes read. Now... my trans tanked completely... and there was no way too replicate the problem to reveal codes. I'm just saying.
Next... have a trusted shop read the codes.
I'm thinking it's electrical-associated. You could pull the steering wheel... spends a lot of time hunting. Me, after my experience, would just take it in too have the codes read.
Wish I had more for you.
