I'm experiencing a peculiar issue with my k-jet B230E. First a little bit of background info. This is a k-jet with no lambda, no oxygen sensor, no cat. It does have a microswitch. I've gone through all the vacuum hoses. The bellow was torn so I replaced that. I also cleaned my throttle body and auxillary air valve.

I followed the steps outlined in the greenbook (thanks to k-jet.org) to set my idle. Idle in N and P is fine at 900rpm. But in D and R it'll go down to 500rpm and if I stay put in gear too long it'll stall.

Initially I adjusted my throttle stop screw to 1/2 turn. Thinking a 20 years old throttle body would surely have some of degree of wrap and play in the plate hinges and spring, I readjusted the throttle stop screw to 1 turn after hitting the base plate. Car won't stall in D or R (rpm up to around 600-700)- good I think. However as a result of more air flow through the plate, idle in N goes up to 1100rpm. I screw in the black idle screw to lower the idle to 900rpm (in N). Idle in D and R goes down to point of stalling and I'm back to square one.

I can't open up the throttle plate at rest anymore using the throttle stop screw. Doing so would cause the microswitch not being in contact with throttle arm (since the arm is too far arm to contact the microswitch)

Any thoughts anyone?

Thanks