Throttle sticking
 

Can someone help diagnose the following problem. Throttle began sticking the other day and drove back home and pulled into the garage. The throttle cable was slack and the throttle plate (butterfly ) was sticking in the open position. The return spring is in place. Seems the throttle plate is a little stiff. Would that indicate that the throttle body shaft needs a rebuild kit with seals and o-rings and all? I cleaned the housing and butterfly with carb cleaner and that did not help the sticking. I can close the throttle plate by grasping the throttle cam and turning to the closed position. It feels a little stiff. Just wanted to see what others thought before I took the throttle housing off and rebuilt it (I am a slightly above average home mechanic). This is a 1987 NA Porsche 944.

Thanks,

944djm