Bought 92, 240sx. Noticed weird problems..

[XxDriverxX]

Hello every body..

I just bought a 1992 240sx LE, with 130K on the engine.  I took it out tonight for the first time and noticed the following:

1) It's an automatic, when I change to Drive or Reverse, the car sometimes Jumps.. Feels like someone or something hitting it from the back or the front. Any ideas what that could be? My mechanic didnt notice that (maybe cause he didnt drive it! GRR) but he tells me he liked the condition of the transmition, and says it's fine.

2) When I'm driving and I slow down to 60km/hour or less, I remove my foot off the gas and break. The moment the RPM hits 1000, it feels like someone taps on the break, at the same time the rpm jumps back to 1500, then again down to 1000, small tap on the break, then jumps to 1400, and so on till it's going slower that 30km/hour. This is VERY weird.. Any ideas?

Can any one help?  I took it toamechanic ysturday he didnt notice all that..

thanks