transmission problem
 

i recently bought a light blue 2000 camry xle v6 with 138,000 kms.
it was ok when i took it for a test drive but the following morning, i noticed that it wont shift to 3rd gear unless it reached 3,000 RPM. this went on for a couple of days until 1 morning i decided to maintain the RPM at 2000. it shifted to 3rd gear after about 3-4 minutes which suggests the transmission was cold and was trying to warm up or there's a sticky solenoid somewhere, or something else. Changing the fluid didn't help.
1 more thing, when i get to 100km/h, the RPM is at 2500.
isn't it supposed to be around 2000? when i reached 120km/h it was at 3000 RPM! i dont feel any lockup torque converter engaging so its either it doesnt have one or it's malfunctioning. can someone please comment on this? Thanks!