01 corolla slams into gear

[sky jumper]

when shifting from P to R or P to D the tranny slams into gear. once engaged it drives/shifts fine. then it slams back into P.

I noticed a second cable connected to the throttle body that is sticking. there's the main throttle cable connected to the gas pedal that is fine, and then another cable heading off the other direction that sticks - i.e. it will pull out when the throttle is depressed, but does not go back in when the throttle is lifted.

also, I noticed when viewing live OBDII data that the absolute throttle position never quite goes to 0. it does increase when the throttle is depressed, but never returns to 0. it stays at 9%. however, the car does idle at a normal 700 rpm.

I think the sticky cable somehow controls/affects the shift mechanism, but I'm not sure. does anyone have experience with this? thanks!