I am worried about a BMW 320i gearbox and low idling

Dear experts. I am looking at buying a BMW 320i 3 series, 1993 model. It has 180 000 kms on the clock and is very good condition. It is an automatic transmission. I am worried about a few things though. Upon viewing it this morning, the car was idling extremely low which I suspect could be both the idling and the timing. I believe I can have this fixed at a local garage. It is not smoking at all and there are no leaks around the engine. It is not over fueling or over-heating. One worry is that when driving the car, it has extremely sharp gear changes. It "jerks" from 1st gear into 2nd gear with a force after revving to around 3500 revs. I am worried that this is a major fault with the gear box. What is your opinion on this? I really do not want to buy a problem car?