1973 450sel stalls as throttle plate moves open

[ataglancemotorsports]

Had customers car dropped off few days ago -- dont know much about these and dont have a lot of information about them.

Here is scenario --
Starts up great idles for days on end -- as soon as throttle plate is moved even slightly engine shuts off -- have to crank it til it fires back up like it is flooded but of course cant use throttle or it wont start at all.

fuel pressure is running 35 psi into fuel dampeners. --

smells rich --

tried blocking off auxiliary air valve -- valve is still open slightly at idle with it warm.

pulled throttle body off and cleaned contacts for throttle position sensor -- I have the proper resistance at idle and then moves open and closed up til it reaches full throttle.

it seems like as soon as it clicks for coming off of throttle that it shuts down engine like you just shut off the key. Then it is hard to start(cranks long time) til it fires back up and clears itself out.

any thoughts would be helpful. thanks.