RPMs high when on the highway

[PontiacRacing]

I have a 1999 Pontiac Sunfire. I had the sunfire for quite a while and the then the tranny blew. i gave it back to my mom and she paid to have it fixed. then she gave it back to me. now the rpms are over 3 grand when im goin 75 mph on the interstate. it wasnt like that before. now i thought it might be a 3 speed so i checked the reciept from the people who did the work, and it said 3 speed. ok, but i feel 3 shifts which would make it a 4 speed. does any body else have this prople with their car. what r ur RPMs on the highway? how would i fix this. i think im gonna have to get a new tranny right? please help. no sarcastic remarks please. i am a mechanic.

 

[melsg5]

did you check if there is a problem with the lockup torque converter?

 

[PontiacRacing]

well im a mechanic but i havent got to the point of transmissions yet. im only 19. could u help me out. whats the lock up on the torque converter.

 

[Sibbles]

Lock up torque converter locks the slip of the automatic in. kinda like a 5 speed and a clutch. Generally if the LTC is working right it should drop your rpms about 400 rpm. However this is generally based on engine temp, consistancy of speed and engine rpm over a set time.