i just got my car back from having my new tranny, 3000 stall tc, comp cams 503 cam, and hsr installed. when i took it out from the mechanics, i noticed that it would make a thump from under the car once and a while. i adjusted the tv cable and the thump seems to have gone away, but there's still something wrong with the car that didn't go away. when i go into 4th gear, i notice that the rpms move up and down maybe a hundred, two hundred rpm's. it sounds like the car's going "wa wa wa wa wa wa wa wa"... it's a subtle noise, but it's noticeable. it's like the rpms are surging. does anyone know what could be causing this? tia

 

How fast are you going when it does it? It sounds like your torque converter clutch is engauging and disengaging. If its happing in the 40-50 mph range it is a "normal condition". There is a kit available from major part suppliers that helps to eliminate the "normal condition".