Bowden cable that controls both push and pull operations on the lever to put the tranny in P-R-N-D-3-2
There is a cluster on the driver's side of the intake manifold-it's where the cable from the throttle connects. On my 87, the top cable on the outside of the cluster is the one that connects to the tranny. It is terminated in a socket that has a threaded base where the cable screws into it and a lock nut. On my 83, the cable was the lower, inside one. Be sure to remove the little wire retainer before you pry the socket off of the ball. The first adjustment should be to tale up all of the loose slack. Good luck.
87 S4 A/T
There should be several connections to your throttle assembly; one from the accelerator pedal, one from the cruise control, one from the
transmission, (This is what I referred to as the pressure modulator cable-but that is my name for it-I'm not sure what the correct technical name is), and one more that I have forgotten where it goes-probably the fuel injection. As I remember from my 83, the transmission cable is connected to a ball at the bottom of the throttle lever assembly where it is fairly hard to get at. It is connected by a socket which has a small retaining wire pin which must first be removed and then the socket can be pried off of the ball. There is a lock nut which must be loosened and then the socket can be screwed either in or out of the base of the socket, which should be shortened to raise shift points and firm up the kickdown to first gear if that hasn't been working. I would move it about two millimeters and then drive it to evaluate the effect.
Porsche makes a kit for replacing the pressure modulator cable which includes a new, adjustable termination for the throttle end which can be used with your existing cable The part # is 928 423 901 02.
First let me say that I am not an expert in any sense of the word, I am just passing on the experience that I had with my 87 S4.
The throttle idler cluster on my car has four cables hooked to it:
two come up from the left side of the engine and these are the cables from the accelerator pedal and from the cruise control. The cable hooked to the ball on the top, right (passenger) side of the cluster is routed down to the throttle plate in the LH Jetronic fuel injection. The cable on the top, left, nearest to the left fender is the pressure modulator cable. To adjust it you would have to loosen the lock nut where the cable goes into the base of the socket, remove the retaining pin that helps to hold the socket onto the ball of the cluster, remove the socket from the ball and then unscrew the cable out of the base of the socket-I would suggest you try about 1/8 inch at a time, being sure to mark your starting point so that you can return to it when you wish. Driving the car after each adjustment should allow you to evaluate the effect of the cable adjustment. Try to run it up to 60 or 70 and then floor it to verify that the kickdown to 2nd is still working. If the cable is stuck in the socket base you may have to use a good quality vise grip to hold it while you rotate the socket. My car wouldn't kick down at anything above about 40 MPH until I had shortened the cable about 1/4 inch. This also raised the shift points.