My girlfriend has a 94 and from what she's telling me, it wont shift out of third into fourth right away unless you really give it the beans and rev it into the 5k range! She says that when shes in the high rpms it doesn't shift for a minute or two, but after that, it's completely fine. I'm thinking it's an electrical issue but I've no idea. Any of you 4runner Guru's that can help would be greatly appreciated.
Also, the transmission has recently been flushed last week and has also had the filter replaced. It's also been rebuilt within the last 3 months.