2000 4runner SR5 P1780 code

[BALDIMAN45]

I just bought a 2000 4Runner SR5 with 116000 miles. I bought it for a daily driver / weekend camping truck. The day after I bought it the check engine light came on and the truck wouldn't shift out of first gear. After about 5 min it started shifting ok. I got on the freeway to come home and it went into netural several times. The next morning I started it up the check engine light was on but it shifted fine. The check engine light has come on and gone off several times in the last couple weeks but the shifting problems only happen about once a week. When they do happen I pull over turn the truck off then start it and it runs like nothing happend. The R light in the dash will sometimes come on no matter what gear it is in. I took it to the dealer and they ran the code and told me that it was the neutral safety switch, so I replaced it and it didn't help the problem. I have a feeling they just want to start changing things until the problem gets fixed. dose anybody have any Idea what could be causing this? I'm kind of at a loss on what to do.