Acceleration/Gear shifting problems/Loudness

[nthug]

I have a 1990 240SX automatic with 204,000 KM

I've noticed that it has problems shifting gears. It will rev past 4,000 RPM and wont accelerate because it won't shift into the next gear. This has happened at 50 km/hr and 80 km/hr. Most of the time its fine, but its happened at bad times (like on the highway, and when trying to overtake ppl).

I'm not sure if it's connected to my bad exhaust. My car got a whole lot louder a few days ago while on the highway and I'm thinking ive got a leak somewhere in the exhaust. The car also seems like its lost some power.

Any ideas?