On a 1996 VdP with 130k miles, the throttle pedal suddenly started to be stiff when driving. If I press it gently it won't move, I have to punch it to get it free. The throttle body is cleaned regularly and was clean when I checked just now, the butterfly and cables seem free to being moved by hand. If I turn off the traction control it makes no difference. There is no problem with starting or idling, and when the engine is off the pedal moves freely and normally, it's only stiff with the engine running. I don't find anything in past postings quite like this, any ideas greatly appreciated.
After further investigation, tweaking things with the engine running - as previously noted, when the engine is off everything moves freely. The pedal gets stiff only when I start the engine. I've now found that it's the throttle body itself that gets stiff - there's apparently some sort of mechanism that retards the butterfly shaft?

 

If you continue to use force on the sticking throttle plate, you will bend the throttle shaft!!