The throttle position sensor, unless it is totally losing contact at a certain place along it's range of movement, is probably not the problem. After verifying that the ignition system is set right, including your timing and dwell, put a gage on the fuel rail and make sure the pressure is correct (~30 psi). Is the pressure constant during idle and also at higher RMP as you approach the stalling point? It could be that you need to change the fuel filter. How's the inside of your fuel tank look?

Also, make sure that you are not running too rich. What is your regulated system voltage? Is the hose well connected between the manifold and the pressure sensor? And is that hose in good condition?

Mark
'84 300D
'69 VW Fastback (D-Jet FI)